Blueberry Crumble Bars
Blueberry Crumble Bars are a delicious late-summer dessert filled with jammy blueberries and topped with a delicious crumble topping. Made with gluten-free flour, these bars are sure to please any crowd.
Servings 9 bars
Equipment
- 8x8 inch square baking pan
- Parchment paper
Ingredients
For the Crust and Crumble
- 1 cup almond flour (120 grams)
- 1½ cups gluten-free all-purpose flour* (260 grams)
- 1/8 teaspoon sea salt
- 1/2 cup light brown sugar (90 grams)
- 3/4 cup melted butter (146 grams)
- 1/2 teaspoon pure vanilla extract
- 1/4 teaspoon almond extract
- Zest of half a lemon
For the Blueberry Filling
- 1/4 cup white sugar (50 grams)
- Zest of half a lemon
- 4 cups fresh blueberries (545 grams)
- 1 tablespoon cornstarch
- 1/2 teaspoon pure vanilla extract
- pinch of sea salt
Instructions
- Preheat the oven to 350℉. Grease and line an 8x8 inch baking pan with parchment paper. Set aside.
Make the Crust
- In a large mixing bowl, sift together the almond flour, all-purpose gluten-free flour, and sea salt. Whisk to combine.
- Add the light brown sugar, melted butter, vanilla, almond extract, and lemon zest. Use your fingers to mix everything together. The final result will be a clumpy, slightly sandy mixture. Set aside 1½ cups to use for the topping.
- Transfer 3 cups of the crust mixture to the prepared 8x8 inch pan. Use your fingers to spread the crust into an even layer across the bottom of the pan. I like to use the bottom of a measuring cup to pack down, smooth out, and level the crust. Set aside while you prepare the filling.
Prepare the Blueberry Filling
- In a medium mixing bowl, use your fingers to massage the lemon zest into the white sugar. This helps release those delicious citrusy oils in the lemon zest and infuse the sugar.
- Measure in the blueberries and cornstarch. Fold together with a baking spatula until the blueberries are coated in the lemon sugar and cornstarch. Add the vanilla extract and sea salt, then fold again to distribute.
- Pour the blueberry filling over the crust, using a baking spatula to spread the filling out evenly.
Assemble, Bake, and Set
- Sprinkle the reserved 1½ cups of the crust mixture over top of the blueberry filling. The topping should mostly cover the blueberries. It's ok if bits of blue are still visible.
- Bake the blueberry crumble bars in the preheated oven for 70 minutes, or until the top is golden brown and the blueberry filling is bubbling up around the edges and between the crumble topping.
- Allow the blueberry crumble bars to cool completely in their pan at room temperature. Once completely cooled, transfer to the fridge for half an hour. This quick chilling makes the bars easier to slice.
- Remove the chilled bars from the pan and slice into nine roughly even bars. Store in an airtight container in the fridge for up to four days. The crust and crumble will soften slightly as the bars age.