Are you sick of Rhubarb yet? I am not. I don’t think that I will ever be, in fact. So here we are again with another rhubarb recipe - this time for Brown Butter Hazelnut Strawberry Rhubarb Crumb Bars. That sounds super fancy, but essentially I took my favourite shortbread recipe (which we used in these mini egg bars), jacked it up even more with some brown butter, then used it as both the base and the topping for these strawberry rhubarb bars. The use of the shortbread in both the base and topping gives a double dose of texture either side of the jammy fruit filling, without having to make two separate components.
The filling for these is super simple - strawberries, rhubarb, a little sugar, and some starch to help bind things. There’s no cooking things down into a jam, it’s just the standard equation for a fruit filling I usually stick by : fruit plus sweetener plus starch. I love how rhubarb cooks down but still holds its shape in these bars - which gives not only that tartness that rhubarb is amazing for, but a little more texture than if you were to cook the fruit down prior to adding to the bars. As long as your base is cooked nicely before adding the fruit, you’re all good to avoid any sogginess.
I kept the ratio of rhubarb to strawberry a bit higher on the rhubarb side, as I wanted the flavour to really come through. You could absolutely switch it up, but be aware that strawberries are a lot more watery than rhubarb, so you may have to tweak the quantity of starch a bit to account for that.
I browned the butter in the shortbread, which is slightly more labour intensive than just using regular butter, but in my opinion is so, so worth it - the toasty brown butter plays off the hazelnuts and brown sugar in the shortbread base, which elevates the whole thing in the most amazing way.
I’ve included directions on how to just use regular butter if you are a little short on time and don’t have time for the butter to cool, or would like to skip that step. These would be perfect for taking to a picnic, or as a simple dessert for a summer dinner - they are so, so good with a scoop of ice cream!
A few wee tips:
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This is important - each batch of brown butter will yield a slightly different amount of liquid. I have added milk into the recipe to account for the moisture loss - my brown butter came out at 180g, so I added 45g milk (to make it back up to 225g). You will need to weigh your brown butter and work out how much milk needs to be added (it’s probably around 45g) - to work this out, weigh your brown butter, then subtract the weight from 225 - that is your milk amount! Or if that’s too tricky, 45g milk will work just great too.
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The brown butter needs a little bit of time (about 45 min) in the fridge to come back to a soft butter consistency so that you can cream it with the sugar
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If you don’t want to brown the butter, you don’t have to, although I think it is a delicious step! If you don’t want to, you can just use 225g of unsalted butter, at room temperature, and you can leave out the milk (which accounts for the moisture loss while browning the butter)
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I used pre-chopped hazelnuts, but if you can’t find those, finely chop some toasted hazelnuts. To toast them, place them on a baking sheet and roast for about 10 mins in the oven at 350°f / 180°c.
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These definitely are easiest to cut once they are properly cool and have time to set - pop them in the fridge to speed this up if you need!
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I actually shot the first test of these, before I tweaked the base a little - so it looks a little on the uncooked side. The final recipe has you cook it a little more!
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The measurements for the fruit are taken after they were trimmed - so the ends chopped off the rhubarb, and the tops taken from the strawberries.
Brown Butter Hazelnut Strawberry Rhubarb Crumb Bars
- Makes 12 bars -
Brown Butter Hazelnut Shortbread
225g unsalted butter, diced
120g brown sugar
45g milk (see notes)
1 tsp vanilla bean paste
1 tsp salt
340g all-purpose flour
60g toasted hazelnuts, finely chopped
Filling
500g trimmed rhubarb, diced
300g trimmed strawberries, diced
½ tsp vanilla bean paste
100g white sugar
3 Tbsp tapioca starch
¼ tsp salt
- PROCESS -
SHORTBREAD
Place the butter in a small saucepan. Heat over medium heat until melted, then continue to cook, stirring often, until it begins to brown and smell nutty. Watch it carefully, as it can easily be over done. It will go foamy, and then be done soon after. Transfer to a bowl to stop the cooking process. Place in the fridge, stirring occasionally, until it is a soft butter consistency (I like to pour it straight into my mixer bowl to save dishes).
Preheat the oven to 350°f / 180°c. Grease a 9” square (23cm) baking tin, and line with two pieces of parchment paper, with the ends extending over the edges of the pan to form a ‘sling’ to help you remove the bars after baking.
In the bowl of a stand mixer fitted with the paddle attachment, cream together the cooled brown butter and sugar until light and fluffy, 2 to 3 minutes. Add the milk and vanilla bean paste and mix to combine. Add the salt and flour, and mix on low until just combined, then add the chopped hazelnuts and mix briefly to incorporate.
Set aside 300g of the shortbread in a bowl, and place in the fridge until needed. Transfer the rest to the lined baking tin, pressing down to form an even layer with an offset spatula or flat bottom of a drinking glass.
Dock the shortbread using a fork, then bake for 20 minutes or until golden. Remove from the oven and allow to cool for 5 minutes. Leave the oven on.
FILLING AND ASSEMBLY
Place the diced rhubarb and strawberry in a medium bowl. Add the vanilla bean paste. In a small separate bowl, whisk together the sugar, tapioca starch, and salt. Add to the bowl along with the fruit, and then mix to combine, ensuring the fruit is evenly coated with the starch mixture.
Transfer the fruit mixture to the slightly cooled shortbread, flattening down gently to make an even layer.
Sprinkle the reserved shortbread over the surface of the fruit - I like to press some of it together with my fingers to make bigger crumbs so that there is some size variation.
Return the baking tin to the oven and bake for a further 55 to 60 minutes, or until the topping is golden brown and the fruit is bubbling. Check it at 40 minutes and tent with foil in for the remainder of the bake time if the topping looks as if it is getting too golden.
Remove from the oven and allow to cool to room temperature (this can be sped up in the fridge). Remove from the tin using the parchment paper sling.Slice using a sharp knife.
Store leftovers in an airtight container at room temperature - they are best the day of or the day after they are made.
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