Homemade Cosmic Brownies have a fudgy brownie layer topped with a smooth chocolate icing and rainbow sprinkles. They are quick and easy to make, and are the perfect easy brownie recipe!
Hi hi! I am just popping in to share the recipe for homemade cosmic brownies with you! I love making homemade brownies, and once I got a great fudgy brownie recipe nailed, I started to play around with variations of it.
I love having one great back pocket recipe that is super versatile and this brownie recipe is certainly it. You can take the one recipe and make cheesecake brownies, brookies, brownie pie, and now these perfect homemade cosmic brownies!
What are Cosmic Brownies?
I didn't grow up eating cosmic brownies as a kid in New Zealand, but heard about them when I moved to the US. The original Cosmic Brownie is made by a brand called Little Debbie's, who make classic packaged treats. We tried them when we lived in New York and once we moved back to New Zealand I decided I should have a go at making a copycat cosmic brownie!
The original cosmic brownie is a chewy, fudgy brownie, topped with a thin layer of chocolate icing, and rainbow sprinkles. I took my favourite brownie recipe, and baked it in a 9"x13" pan rather than a 9" square, giving a much thinner brownie.
Once the brownie is baked, you add a simple chocolate icing, which comes out nice and smooth as it melts from the heat of the brownie. The whole thing is finished off with rainbow sprinkles, then goes in the fridge to chill until you are ready to serve. Super easy, and super delicious.
How to make Cosmic Brownies
Homemade Cosmic Brownies are super easy to make, and I love that the whole process can be done in one go, rather than having to wait for the brownie to cool before adding the icing.
- Make the brownie layer. This is a super easy brownie recipe, baked in a 9"x13" pan until just done. You don't want to over bake them so that they stay nice and fudgy.
- Make the Icing layer. While the brownie is baking, assemble your icing ingredients. You want to start mixing the icing together once the brownie is out of the oven so that the icing can go on while the brownie is hot. Some recipes use a chocolate ganache made from chocolate and heavy cream, but I went with a super easy icing instead!
- Add the icing. Transfer the icing to the hot brownie, and smooth out. The heat from the brownie will melt the icing, making it nice and smooth and flat.
- Add sprinkles. Add your sprinkles of choice to the top of the brownie.
- Refrigerate. This part is important - it is important both for letting the icing set but also allowing the brownie to chill down to be that perfect fudgy, chewy texture and rich chocolate flavor.
- Slice and enjoy! Remove the brownie from the pan and cut into pieces using a super sharp knife.
For all my tips and tricks on perfect fudgy brownies, check out my super easy brownie recipe
My Top Brownie Tips
- Get all my tips and tricks on how to get the perfect crinkly brownie top in my fudgy homemade brownie recipe.
- Plus, follow this easy Instagram video tutorial to cleanly cut homemade brownies!
Cosmic Brownie Sprinkles
The original Little Debbie's Cosmic Brownie has rainbow candies on the top that are basically candy coated chocolate chips.
I looked all over for these to find somewhere that ships them to New Zealand, and ended up getting them from a place in Australia. You could also use these rainbow chips, or you may be able to find them at craft stores. You could also use mini M&M, or the sprinkles of your choice!
How to avoid crinkly icing on your cosmic brownies
This is a strange thing to write a paragraph about, but I know a lot of you love attention to detail as much as I do. When I was testing this cosmic brownie recipe, I was having problems with the icing cracking as it cooled, or as I pulled the brownies out of the pan. There were a few reasons for this, and this is how I fixed them:
- The frosting was going on when the brownies were hot from the oven, causing the middle of the brownie to sink and the icing to crack when it cooled. Leaving them to sit for about 5 minutes meant that the brownie has time to set a little before the frosting goes on.
- The sprinkles were going on when the icing had just gone on, and so they sunk and made cracks. Leaving the icing to sit for 1-2 minutes after smoothing it on means the sprinkles sit on the surface.
- When I was testing, as I usually do, I was greasing the pan before adding the parchment paper to help the paper not wiggle when the brownie batter is added. This meant that when the cosmic brownies were chilled, it was hard to remove the paper from the pan, causing the icing to crack. Using an ungreased pan and parchment paper helped to fix this!
Frequently Asked Questions
What tools and equipment do you use?
You can find a full list of the tools and equipment I use on my products page
How do you store Cosmic Brownies?
Store cosmic brownies in an airtight container in the refrigerator for up to five days.
Can these be made gluten free?
I haven't tested it specifically but brownies generally are ok being made with a cup for cup gluten free flour replacement.
Can you freeze brownies?
I haven't tested freezing these brownies in particular, but if I was going to I would leave off the sprinkles, and place them in an airtight container in the freezer, then defrost either in the fridge or at room temperature.
❤️ Made this recipe and love it? ❤️
I would LOVE for you to leave me a review and star rating below to let me know how you liked it! Also, please make sure to tag me on Instagram!
Answers to your baking questions
Over the years, many of you have asked me questions about:
- baking in grams
- adjusting oven temperatures
- what kind of salt to use
- and many more!
I've curated and answered them all for your easy reference in this frequently asked questions post!
Cosmic Brownies
- Prep Time: 20 minutes
- Cook Time: 20 minutes
- Total Time: 40 minutes
- Yield: 16 servings 1x
- Category: Brownies
- Method: baking
- Cuisine: american
Description
Homemade Cosmic Brownies have a fudgy brownie layer topped with a smooth chocolate icing and rainbow sprinkles. They are quick and easy to make, and are the perfect easy brownie recipe!
Ingredients
Brownie
- 200g dark chocolate (I used 72%), coarsely chopped
- 180g unsalted butter, cold from the fridge is fine
- 15g dutch process cocoa powder, or regular unsweetened cocoa, sifted
- 3 large eggs (about 150g not including shells), at room temperature
- 200g caster sugar
- 100g light or dark brown sugar
- 2g (½ tsp) kosher salt
- ½ tsp vanilla extract or vanilla bean paste
- 100g all-purpose flour, sifted
Chocolate Icing
- 250g powdered sugar, sifted
- 25g cocoa powder (regular or Dutch Process is fine)
- pinch of salt
- 60g unsalted butter, cut into small pieces, at room temperature
- 40g boiling water
Rainbow Sprinkles of your choice to finish
Instructions
BROWNIE
- Preheat the oven to 350°f / 180°c. Line a 9”x13" (20cm x 30cm) pan with parchment paper, leaving a little extending up the sides of the pan to help remove the brownie. Please see notes for pan information.
- In a heatproof bowl over a pan of simmering water (make sure the bowl does not touch the water), combine the dark chocolate and butter. Heat, stirring frequently, until the chocolate and butter are melted and the mixture is smooth. Alternatively you can do this step in the microwave-safe bowl - microwave for 30 second increments, stirring well after each until the mixture is smooth and combined.
- Sift the cocoa powder over top of the chocolate and butter mixture and stir until well combined.
- In a large bowl, combine the eggs, granulated sugar, and brown sugar. Mix on medium to high speed with an electric handheld mixer for 2-3 minutes until the mixture has lightened and increased in volume. This step can also be done in a stand mixer using the whisk attachment.
- Add the chocolate mixture and mix to combine. Add the salt and vanilla and mix until incorporated.
- Add the flour and incorporate by hand until the mixture is smooth and does not have any lumps.
- Transfer the batter to the prepared pan, and tap the pan on the counter a few times to ensure there are no air bubbles. Leave to sit for a minute or two then bang again to ensure there are no bubbles.
- Bake the brownies for 18 to 20 minutes, checking after 15. You are looking for the edges and top of the brownie to be set, and when a skewer is inserted into the middle, it should come out with a few moist crumbs attached. You are best to lean toward under baking than over baking. While the brownie is baking, prepare the icing ingredients so you are ready to start making it when the brownie comes out of the oven.
- Remove the brownie from the oven and leave to stand for 5 minutes before starting making the icing.
CHOCOLATE ICING
- Sift together the powdered sugar, cocoa powder, and salt. Add the butter and mix until the butter is coated by the dry ingredients.
- Once the brownie has sat for 5 minutes, add the boiling water to the icing ingredients, and mix until the butter is melted and the icing is evenly combined. I like to start with a spatula and switch to a whisk to help the icing come together.
- Add the icing to the hot brownie, then carefully use an offset spatula or the back of a spoon to smooth the icing down. The heat from the brownie will melt the icing, helping it to smooth out.
- Once the icing is smooth, leave it to stand for 1-2 minutes, then add the sprinkles of your choice.
- Place the cosmic brownies in the fridge until completely chilled, a few hours or up to overnight.
- Remove from the pan using the parchment and slice into pieces using a sharp knife.
- Store in an airtight container in the fridge for up to 5 days.
Notes
I use a metal USA pan brand 9x13" pan. If you use a glass or ceramic pan, or one with rounded edges, you will need to likely adjust the bake time, as glass and ceramic do not conduct heat the same way as a metal pan does, and a rounded edge pan will be smaller than the pan that I used. Please make a note of this and adjust the bake time accordingly.
Comments
stacy says
these look amazing!
Caribou says
Can't wait to try these!
Kelsey says
This is a great recipe! Tastes so good.
(Make sure you line all sides of the pan with parchment. The icing hardens when chilled and sticks to the pan)
Michaela says
This is the most incredible brownie I have ever tasted. I have been eyeing up some of your recipes for a while and decided to finally give this a crack today. I love that the recipe is in grams, it makes baking so much more efficient. I am now converted to chilled brownies, I’ve always been a hot out of the oven or stored at room temp but chilled brownie is something else!
Erin Clarkson says
Hahah yesss this is what I like to hear!
Kate says
Any way to convert to ounces or cups without looking up how to convert each ingredient from grams?
Erin Clarkson says
Not really sorry. There is a note above the recipe regarding this - happy to recommend a scale if you like, they are a great thing to own.
Becky says
Ok so I’m a massive fan of brownies but have never found a recipe I like! Until this. They are super easy and oh my gosh, eating them out of the fridge is honestly the only way to eat brownies! Erin has done a fantastic job of explaining her recipe and these are my go to for a crowd pleasing brownie
Anna says
These are the best brownies and my kids/husband ask for them all the time. The recipe is very easy and reliable. It has become my new go to recipe.
Jess says
Made these today & they are THE BEST!!
I’m notoriously terrible at brownies but they came out perfect (as does the OG brownie of yours too!) & I love the fact I can ice these hot, add some colourful topping depending on the occasion & they’re good to go.
Made with staple ingredients I have in my pantry but pack such a delicious, decadent, fudgy flavour.
I’m a huge fan of your recipes & thank you for all the extra details you include in your posts, it’s so helpful!
Jessica says
So good! The fudgy texture was just like it’s namesake, and the overall taste was amazing. I will definitely be making these again and again 😍
Jessica says
Wish I could give it more than 5 stars!
Hudson says
yummy ( is good )
Georgina says
This is the absolute best brownie!! Comes out just like the picture and is oh so delicious!!! My whole family loved it and I can’t wait to make more ❤️
Jenn says
The texture is out of this world! They were east to make and so chocolatey. They’re delicious chilled or room temperature. Will definitely make them again!
Carissa says
These are so fudgy and delicious!! I’m American and I love cosmic brownies, but it’s been a while since I’ve had them. I came across this recipe while on your blog so I just had to try it. I was not disappointed and I will definitely make these again!
Nadya says
Such a fun recipe!! It was so very satisfying to spread that frosting in warm brownies and set so beautifully!! I appreciate your hard work to perfect your recipes Erin! I also enjoyed cutting and eating these brownies cold ☺️ I am also thankful for the weight of the eggs so I can easily half the recipe without guessing how much half and egg is. Grams always for the win!!
Nadya says
oops on* and an* egg
Taylor says
These are insane!! We grew up on cosmic brownies as kids and these were so nostalgic. Made them for Thanksgiving and my family ate them over every other dessert on the table! Definitely saving this one!
Janet C. says
My kids are begging me to make this but I only have a 8x8 square pan. I assume it would work but do you have a suggestion on how much to up the baking time? Thank you!
Erin Clarkson says
Hi! I have a pan calculator on my site - it is linked above the recipe! 🙂
Marissa says
Turned out wonderfully, even with my first go being a double batch in an 11"x15" glass dish. Everyone at the party loved them!
Jennifer Smith says
I made this recipe! I followed the fabulously detailed instructions as always, and had no issues. I cut mine in to 24, they've very intense so you don't need big slices.
Sarah says
Like cosmic brownies, but way better. Super nostalgic and delicious!
Stephanie R says
Made these for a charcuterie board themed night. I brought the dessert board and included these for a 90’s vibe. They were a hit. Not usually a frosting person, but this worked well with the brownies
Jocelyn says
Yum yum yum!! These turned out fantastic and they're easy to make!!
Jillian Willmott says
I just made a gluten free small batch of these and they turned out really well, eating pretty much the same as the wheat flour version. They got rave reviews from my caeliac niece and brother in law. Great recipe!
Grace says
I would first like to thank Erin for providing these fantastic recipes. I found her blog when I was living in the remote Arctic and hadn’t made any friends yet. Baking her recipes gave me a sense of purpose, and I would bring the treats into my husband’s work to share with his coworkers (I made friends pretty quickly when I brought the brown butter cinnamon rolls in for all the pilots on base hahaha).
These are truly the best brownies I’ve ever had. The recipe is very easy to follow, and they taste incredible. My father in law doesn’t really like chocolate in baked goods, but when I make a batch of these he is all over them!
Jane says
These are so good and so easy! I have made these for multiple parties and everyone knows exactly what they are when they see them and the taste is so perfectly cosmic brownie. Delicious and nostalgic and just ever so slightly elevated from the original store bought version.
Amanda says
These are so insanely good! I intended to take a photo but they got eaten too fast. Can't wait to make again.
Ashley says
The brownies turned out great! I decorated mine with M&Ms. However, the icing was too sweet for my preference. Is there a way to cut down the sugar without losing the quantity to cover the 9x13 pan? Please let me know - otherwise awesome directions and detailed steps!
Erin Clarkson says
Not really sorry! Just do less icing?
Em says
My family and I LOVE these cosmic brownies, super easy recipe and even when I was rushing and out the oven on the wrong temp they still came out epic. Just divine, chocolate buttery goodness!
Taylor Abbey says
I’m pretty sure I’ve commented on these before but these are my go-to brownies! The edges are my secret stash before parties!
Mallory says
These brownies were absolutely delicious! Will definitely be adding them to the recipe folder we use in our house!!!
Mallory says
These were absolutely amazing! I’ll definitely be making them again!
Connie says
Great recipe! I followed it exactly and was pleasantly surprised because I thought the batter was thin and I didn’t think it would rise but it came out perfectly!! I baked for 20 minutes. I used Valentines sprinkles & I will definitely bake these year round!
J says
I think I will make them again as the flavor was good but it was too fudgey for me. It felt like I was biting through a hunk of set icing rather than brownie. Next time I will let the brownie cook just a little longer. I took mine out at 15.
Erin Clarkson says
Hi! Yep they will definitely need a little more time in the oven!
Joyce says
Hi Erin! Wondering once these are firmed up, will the frosting be hard enough to packaged individually without it smearing everywhere? And if sending to a school, does the frosting soften once out of the fridge for a couple of hours? Thank you!
Erin Clarkson says
Hi, yep they should be good as long as it's not too hot 🙂
Natalie K. says
Made these for my future mother-in-law for Mother's Day, and she said these were the best fudgiest brownies she's ever had! I halved the recipe for an 8×8 pan without issue (thank you weight based measurements!).
Jenny says
These are exceptionally good, perfectly fudgy brownies. I've made them several times now. Thank you, Erin, for an excellent recipe.
Erin Clarkson says
Yay they look so good!
Phoebe says
The best brownies I’ve made in a long time! A big hit when brought to a shared pot luck 🙂 Will definitely be making it again soon!
Hannah says
These were soo fun to make and eat! I did have to bake them a little longer and keep a very close eye on them because they’re so dense and my oven isn’t super accurate.
Fiona says
These are the constant request I get asked to make for family get togethers. So yum and looks good no matter what you put on top. I’ve done mini marshmallows, chopped nuts, sprinkles ect
Elle says
Can the iced brownies be frozen? Is there a way to me the brownies one day and ice it the next week?
Erin Clarkson says
Hi, I haven't tried sorry! You can, the icing just won't be smooth like in the pictures but if that is fine with you then it will work great
Kirsty says
These are the business. Made them for work and everyone loved them. I was a bit sceptical about the fridge brownie situation but am now on board. Make these now!
Alicia says
Hello! These brownies look great! I would love to make them. Unfortunately I'm a cup/tsp baker since I dont own a scale. Can you recommend a scale, please? I'd like to branch out with my baking. Thank you!
Erin Clarkson says
Hi! Yayyyyy welcome to the club it's the best one! I use an escali scale and really like it but honestly anything you can use is going to be more accurate than cups! <3
Tay says
What brand of sprinkles did you use? They look so similar, having a hard time finding them. Thanks!
Erin Clarkson says
Hi, there's a section in the blog post on this 🙂
Sabrina says
I’m wondering if anyone has tried freezing these? I want to cut them up and freeze for packed lunches, but I’m not sure if the frosting would be weird when they thaw?
Erin Clarkson says
I haven't tried but I have some in my fridge so will pop some in the freezer and test for you 🙂
Sabrina says
I tried it and it worked really well! I cut them into little squares so they could get put into packed lunches and it worked great. They don’t freeze solid either, so you can even eat them straight out of the freezer 😋
Erin Clarkson says
Oh perfect! Omg I bet they are so yum fresh from the freezer!
Anel says
Made this for my family this weekend and its SO delicious! The icing on top is a bit too sweet for me but its balanced out really well by the brownie base. Brownies are more cakey than fudgey but still delicious!
Erin Clarkson says
Hi! The brownies should be fudgy - try baking a little less time 🙂 so happy you enjoyed!
Amy says
My new favorite brownie recipe!! I especially like these chilled. Fudgy chocolatey goodness. And I love that everything is by weight; it makes it so easy to convert for different pan sizes. With all the fun Easter candy around right now, I opted to top with malted milk mini eggs - turned out super cute 🙂 Thanks for a great recipe, Erin!
El says
Made them in a muffin tin (with liners), worked out great and everyone loved them!
Erin says
So yummy! Loved making these - recipe was super easy to follow and the result was fantastic.
JC says
Thank you, this is an excellent recipe. I messed it up by not sufficiently adjusting the baking time due to using a smaller pan and dumping the icing on top, creating a bit of a liquified situation, that firmed up very, VERY nicely in the fridge overnight. The weight based measurements are *chef's kiss* and anyone who thinks messing around scooping and leveling is easier than dumping in to a bowl on the scale just watching the numbers has never tried it!
Sarah says
The reason I rated it a one is because even the base brownie wasn’t stellar. So, it was a lot of work for a disappointing brownie.
My icing top didn’t set properly, but I know that I accidentally got an extra 9g of boiling water in it, so that’s on me. However, that’s what made the brownie even more disappointing. The batter was also so thick it was difficult to spread—piping it would’ve been more effective.
This recipe won’t be a repeat for me. (Which is a shocker because I came here from some of the other recipes I love!!)
Erin Clarkson says
Hi! So sorry it didn't work for you - the extra boiling water definitely wouldn't have helped!
Emily says
Absolutely love these brownies!
Perfect every time I make them
Lydia says
Every brownie should be iced and you can't change my mind 😅! These are sweet and rich - adding the icing while the brownie is still warm gives the whole thing the most magnificent fudgy texture once set. Loved equally by adults and children alike, I especially liked them straight from the fridge. Don't skip the sprinkles.