A buttery shortbread-like base, juicy blueberry filling and a crumbly topping — these blueberry crumble bars are easy to make and utterly delicious.
This post was updated May 21, 2024 with new photos and a slightly adjusted recipe for thicker bars and a juicier blueberry filling.
These blueberry crumble bars combine a tender, buttery shortbread base with a vibrant, juicy blueberry layer and a crunchy crumb topping. They travel better than a loose crisp or crumble and can be made with fresh or frozen berries (note: frozen berries may require a bit more bake time). The finished bars are perfect for dessert with ice cream or as a sweet snack with coffee the next morning.
Making Blueberry Crumble Bars
This version is inspired by Deb Perelman’s Blueberry Crumb Bars from Smitten Kitchen. The main changes here increase the butter-to-flour ratio for a richer, more shortbread-like base, add brown sugar to the topping for a deeper golden color, and thicken the overall bars for a heartier slice.
Start by preparing the blueberry filling: toss the berries with a little sugar, cornstarch (cornflour in some regions) and lemon juice. The cornstarch thickens the filling during baking so the bars don’t become runny, while the lemon juice helps soften the berries and brightens their flavor without tasting overtly lemony.
Next make the shortbread dough used for both the base and the crumble topping. Whisk together the flour, sugar and baking powder, then cut in cold, cubed butter and an egg yolk until the mixture is crumbly but holds together when squeezed in your hand. Cold butter is important here — as it melts in the oven it creates steam pockets that give crumbles and shortbreads their desirable flaky, crumbly texture.
Recipe Tip
Use cold butter, not room temperature. Cold butter yields flakier, crumblier pastry as it bakes — ideal for both the shortbread base and the topping.
Assembling & Baking the Bars
Reserve about 1 cup of the crumbly dough for the topping, then press the remaining dough evenly into the bottom of an 8×8 inch prepared pan to form the shortbread base.
Spoon the blueberry mixture over the base in an even layer. If there is excess juice from thawed frozen berries, leave it behind in the bowl so the bars don’t get soggy.
To make the crumble topping, return the reserved cup of shortbread mixture to a bowl and add a tablespoon each of flour, granulated sugar and packed brown sugar. Work these in with a fork or pastry cutter until the mixture becomes even crumblier, then sprinkle and press the crumbs over the blueberry layer.
Bake the bars at 350°F (180°C) until the berries are bubbling and the topping turns a light golden brown — about 40 to 50 minutes. If you used frozen berries, add roughly 10 more minutes to ensure the filling is fully bubbling and thickened.
Recipe Tip
Allow the bars to cool completely before slicing. Cutting while warm leads to a runny filling and messy slices — patience yields clean, neat squares.
The balance of juicy fruit, rich shortbread and crunchy crumbs makes these blueberry crumble bars a crowd-pleaser. They’re straightforward to prepare and make a lovely dessert, picnic treat or bake sale item.
If you enjoy these bars, you might also like other blueberry desserts from the same collection, such as Blueberry Coffee Cake, Blueberry Oatmeal Crumble Bars and Lemon Blueberry Cake.
Blueberry Crumble Bars
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Equipment
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8×8 inch (20×20 cm) pan
Ingredients
Blueberry Layer
- 2 cups blueberries (about 250–300 g if fresh), fresh or frozen
- 2 teaspoons cornstarch, use 4 teaspoons if using frozen berries
- 1 tablespoon lemon zest
- 1 tablespoon lemon juice, freshly squeezed
- 1/4 cup granulated sugar (50 g)
Shortbread Base & Crumble Topping
- 1 and 1/2 cups all-purpose flour (188 g)
- 1/2 cup granulated sugar (100 g)
- 1/2 teaspoon baking powder
- 1/4 teaspoon salt
- 3/4 cup unsalted butter (170 g), cold, cubed
- 1 large egg yolk
- 1 tablespoon packed brown sugar
- 1 tablespoon granulated sugar
- 1 tablespoon all-purpose flour
Instructions
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Preheat the oven to 350°F (180°C). Line an 8×8 inch square pan with foil or parchment, leaving an overhang for easy removal.
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In a medium bowl, toss together the blueberries, cornstarch, lemon zest, lemon juice and granulated sugar. Set aside.
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In a large bowl, whisk the flour, granulated sugar, baking powder and salt.
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Cut the cold cubed butter and the egg yolk into the flour mixture using a pastry cutter or two forks until the mixture is crumbly but holds when squeezed.
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Reserve 1 cup of this mixture for the topping. Press the remaining dough into the prepared pan to form an even base.
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Spoon the blueberry mixture evenly over the shortbread base. If using frozen berries, leave any excess liquid behind.
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To the reserved cup of dough add 1 tablespoon flour, 1 tablespoon granulated sugar and 1 tablespoon brown sugar. Work in with a fork until very crumbly, then crumble over the blueberries.
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Bake 40–50 minutes, until the blueberries are bubbling and the topping is golden. Add about 10 minutes if you used frozen berries.
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Cool fully at room temperature (about 3–4 hours) before lifting from the pan and slicing into squares.
Notes
- Nutrition: Values are estimates per bar when the pan is cut into 9 large squares.
- Storage: Store in an airtight container in the refrigerator for up to 4 days.
Nutrition
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Recipe adapted from Smitten Kitchen.