Super easy M&M cookie bars are thick and chewy, and loaded with M&Ms and chocolate chunks. These cookie bars are all the taste and texture of a cookie, but baked into a bar!

Hi hi! I am just jumping in to share the recipe for these M&M Cookie bars! This easy cookie bar recipe is a twist on my regular M&M cookies, with a few tweaks made, and baked into thick and chewy M&M cookie bars rather than individual cookies.

I love making homemade cookies, especially my perfect chocolate chip cookie recipe, but sometimes you don't want to put in all the effort it takes to make cookies from scratch, but you still need to scratch that cookie itch. This is where these M&M cookie bars come in. They have all the taste and texture of an M&M cookie, but you spread the batter into a pan and the whole thing goes in the oven. No chilling required - easy M&M cookie bars in under an hour.

If you love cookie bars make sure to also check out my chocolate chip cookie bars recipe, and my brookies recipe!

How to make M&M Cookie bars
Can cookie bars be made ahead of time?
How to cut cookie bars

cookie bars on wire rack with m&ms and knife

These M&M cookie bars are super easy to put together. They are made with an egg yolk cookie base, which I use in my M&M cookies and my egg yolk chocolate chip cookies. Using egg yolk gives the cookies a super chewy finish, and is a great way to use up extra yolks you may have on hand. I have a bunch of egg yolk recipes on my site if you need any extra inspiration!

Whip together wet ingredients. This recipe uses melted butter, so there is no need to wait for butter to come to room temperature. Combine with the brown sugar, granulated sugar, yolks, and vanilla in a large bowl. Whip until thick and lightened in colour - this step will give you that nice crinkly finish on your cookie bars.
Add dry ingredients. Add the flour, baking powder and salt and mix to combine - don't mix too far at this point to avoid over mixing.
Add mix-ins. Add the chocolate and M&M candies, and stir to incorporate. I like to do this part by hand to make sure most of the M&Ms stay intact. I use chopped chocolate, but you can use chocolate chips if you like too!
Press the dough into the pan. I use an 8" pan, lined with parchment paper to ensure that the cookie bars are easy to remove afterward. Press the dough into the pan, flattening down with a spatula, then using an offset spatula if you want it super smooth.
Bake. Bake the M&M cookie bars for 20 to 22 minutes until perfectly golden brown, then remove from the oven and leave to cool in the pan before slicing and enjoying.

These M&M cookie bars are great to make ahead of time - you can make them a day or two ahead, and store in an airtight container at room temperature until you are ready to serve. They keep for four to five days at room temperature.

If you would like to freeze them, layer them in an airtight container with parchment paper between the layers, then freeze. Defrost at room temperature or in the fridge - defrosted cookies often benefit from a quick zap in the microwave to refresh before eating!

If you would like to make the cookie dough ahead of time, you can press it into the baking pan, cover in plastic wrap, then place the whole thing into the fridge and bake from chilled, for warm M&M cookie bars on hand for an easy dessert!

I get asked this question often - how do you get a clean cut on your cookie bars and brownies? There are a few wee tips for getting a nice clean cut:

Use a sharp knife. This makes a huge difference. Using a really sharp knife for cutting things gives you a nice clean cut.
Wipe the blade between cuts. Having a clean blade between cuts means that you reduce the chance of crumbs.
Let the cookie bars cool. If you can't wait, then just go for it, it all ends up mixed up in your tummy. But if you would like a super clean cut on these M&M cookie bars, leave them to cool first before removing from the pan and slicing.

A few more tips for cookie bars:

Don't overbake them. If you over bake your cookie bars, they will be slightly dry around the outside. You are better off erring on the side of underbaked and they finish off baking when you remove them from the oven.
To test for doneness, you can insert a toothpick into the middle of your bars - it should come out with a few crumbs. Otherwise I like to do it by touch and sight - you want to look for the edges to be puffed up slightly and the top of the bars to be set.
If you want that slightly crinkly top on your M&M cookie bars, make sure that you whip the butter, sugar and egg yolks together well in the first step. Having room temperature eggs will mean that they whip up nicely too.

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

Can I add other mix-ins?
Add whatever you like! These M&M bars would be great with nuts such as walnuts or peanuts added (toast them first), or you can use different kinds of M&M candy (the peanut butter ones would be amazing) or add in some white chocolate chips. You can also mix up the kind of chocolate you use - I used dark chocolate but milk chocolate would be delicious too.

Can I make this recipe in a stand mixer?
Yes you can, but I find it just as easy to use a large bowl and a whisk! You can also use an electric hand mixer.

For more cookie and bar recipes, check out:

Made this recipe and love it?

If you made this recipe then I would LOVE for you to leave me a review below to let me know how you liked it! Also, please make sure to tag me on Instagram if you make it!

A note on salt and oven temperature

It is important to note the type of salt that is called for in a recipe. I use Diamond Crystal salt throughout my recipes - if you use a different sort of kosher salt or regular table salt you will need to adjust accordingly as some salt is 'saltier' than others. Morton's salt is twice as salty, so you will need half the quantity. Same goes for a regular table salt. I am working to get gram measurements throughout my recipes for salt but still getting there.

All oven temperatures are conventional unless otherwise stated. If you are baking on fan / convection, you will need to adjust the temperature. An oven thermometer is a great investment to ensure that your oven is the correct temperature.

Using the double / triple function in the recipe card

You will notice that there is a '1X' '2X' '3X' button in my recipe card. This can be used for doubling or tripling a recipe. However, please note that this only doubles the ingredient quantities in the ingredients list and NOT in the method. If there are quantities or pan sizes in the method of the recipe (for example weigh out 150g brown butter), you will need to scale this number manually. It will also not change the baking time in the recipe so you will need to adjust this yourself too. It is always a good idea to read through a recipe fully before doubling it just to check this. If you would like to scale this recipe or convert for another pan size, use my calculator!

Tools and equipment

For a list of my go-to tools and equipment, I have a post you can refer to here.

Why is this recipe in grams?

I post my recipes in grams as it is the most accurate way to bake. Cups are not only inaccurate but they vary in volume worldwide. There is no way for me to provide one cup measure that works for everyone. However, posting in weight fixes this issue. If you would like the recipe in cups you are welcome to convert it yourself via google, but please do not ask me to do it for you as I am not comfortable providing a recipe using a method that I have not tested. Baking with a scale is easy, accurate, and also makes cleanup super simple. Here is the scale that I use if you would like a recommendation! Here's to accurate baking!