Jammy Blueberry Crumble Bars with Buttery Shortbread Crust
Blueberry crumble bars are one of those desserts that feel like a treat but come together with almost no effort. A buttery shortbread crust, a jammy blueberry filling, and a crumbly top layer, all from one dough.
They hold up well in the fridge for days, which makes them perfect for packing in lunches or serving at a summer potluck. And the whole thing starts with just one bowl and a baking pan.
What Makes These Blueberry Crumble Bars So Good
The crust and crumble come from the same dough, which means less work and fewer dishes. It bakes up buttery and tender with crisp edges, holding up to a thick layer of blueberries without getting soggy.
The filling is all fruit, cooked down with a little sugar and lemon until it turns thick and jammy. Using frozen blueberries means you can make these bars any season, and they’ll taste just as good as fresh.
Ingredients
- 3 cups (390 g) all-purpose flour: spooned and leveled, not scooped
- 3/4 cup (150 g) granulated sugar
- 1 teaspoon baking powder
- 1/2 teaspoon fine sea salt
- 1 cup (226 g) cold unsalted butter, cut into small cubes: keep it cold straight from the fridge
- 1 large egg
- 1 teaspoon vanilla extract
- 4 cups (20 oz) fresh or frozen blueberries: no need to thaw if frozen
- 1/2 cup (100 g) granulated sugar: for the filling
- 2 tablespoons cornstarch
- 1 tablespoon fresh lemon juice
- 1 teaspoon lemon zest: optional, but adds brightness
Variations / Substitutions
- Swap the berries: raspberries, blackberries, or a mix all work well. If using strawberries, chop them into small pieces first.
- Gluten-free: use a quality 1:1 gluten-free flour blend.
- Dairy-free: replace the butter with a dairy-free stick alternative; the texture will be slightly softer but still buttery.
- Less sweet: reduce the sugar in the filling by 1 to 2 tablespoons for a tarter bar.
- Add a hint of spice: a pinch of cinnamon or cardamom stirred into the filling gives it a cozy edge.
Blueberry Boba Milk Tea makes the perfect drink to sip alongside these bars.
How to Make Blueberry Crumble Bars
Step 1: Mix the Dough
Preheat your oven to 350°F (175°C) and line a 9×13-inch metal baking pan with parchment paper, leaving an overhang on the two long sides. Whisk the 3 cups flour, 3/4 cup sugar, baking powder, and salt together in a large bowl. Add the cold cubed butter and cut it in with a pastry blender or your fingertips until the mixture looks like coarse crumbs with pea-sized pieces of butter still visible.
The mixture will stay dry and crumbly, and that’s exactly what you want. Those visible butter bits are what create the tender, shortbread texture. Stir in the egg and vanilla just until the dough starts to clump together, but stop before it forms a ball. Set aside about 1 1/2 cups of the loose dough for the topping.
Step 2: Cook the Blueberry Filling
Combine the blueberries, 1/2 cup sugar, cornstarch, lemon juice, and lemon zest in a medium saucepan. Cook over medium heat, stirring often, until the mixture thickens and the berries begin to burst, about 8 to 10 minutes. If you are using frozen berries, they may need an extra minute or two.
The filling should coat the back of a spoon and no longer look watery. It will continue to thicken as it cools, so pull it off the heat just as it reaches a loose jam consistency. Let it cool for a few minutes while you press the crust.
Step 3: Layer the Bars
Transfer the remaining dough (the portion you did not reserve) into the prepared pan. Press it firmly and evenly across the bottom with your fingers or the flat bottom of a measuring cup. You want a compact, solid layer so the filling does not seep underneath.
Take an extra 30 seconds to compact the crust well, especially in the corners. Any loose spots can soften and cause the bars to fall apart after baking. Once the crust is pressed tight, spread the slightly cooled blueberry filling over it in an even layer, then scatter the reserved crumble dough evenly on top.
Step 4: Slice and Serve the Bars
Bake for 45 to 50 minutes, until the top is golden brown and the filling is bubbling around the edges. Remove the pan from the oven and let the bars cool completely on a wire rack right in the pan.
Once cool, use the parchment overhang to lift the whole block out and onto a cutting board. Slice into squares or rectangles with a sharp knife, wiping it clean between cuts for the neatest edges. Serve at room temperature.
Tips for Perfect Blueberry Crumble Bars
- Keep the butter cold throughout the process. If your kitchen is warm, pop the bowl in the fridge for a few minutes before cutting in the butter.
- Mix the dough just until it clumps together. Overmixing will develop gluten and make the crust tough rather than tender.
- For extra crunch on top, sprinkle the crumble with a couple teaspoons of coarse sparkling sugar right before the pan goes into the oven.
Bake times can vary slightly with different pans:
| Pan type | Bake time |
|---|---|
| Metal 9×13 pan | 45 to 50 minutes |
| Glass 9×13 pan | 50 to 55 minutes |
Storing and Freezing Blueberry Crumble Bars
Refrigerate Store leftover bars in an airtight container in the fridge for up to 5 days. They are delicious cold or at room temperature.
Freeze Wrap individual squares in plastic wrap and place them in a freezer bag for up to 3 months. Thaw overnight in the fridge.
Frequently Asked Questions
How do I get neat, clean slices?
Cool the bars completely, then lift the whole block out with the parchment and slice with a sharp knife. Wipe the blade clean between each cut.
Can I make these bars ahead for a party?
Yes, they keep beautifully and the flavor improves overnight. Make them up to 2 days ahead and store covered in the fridge.
Can I reduce the sugar in this recipe?
You can cut the filling sugar by 1 to 2 tablespoons for a tarter bar. Reducing the sugar in the crust will change the texture, but a modest decrease of 1 to 2 tablespoons is still fine.
Blueberry Crumble Bars Recipe
Ingredients
Method
- Preheat oven to 350°F (175°C). Line a 9×13-inch metal baking pan with parchment with overhang. Whisk flour, 3/4 cup sugar, baking powder, and salt. Cut in butter until coarse crumbs form. Stir in egg and vanilla until clumpy. Reserve 1 1/2 cups of the dough.
- Combine blueberries, 1/2 cup sugar, cornstarch, lemon juice, and zest in a saucepan. Cook over medium heat, stirring, until thickened and berries burst, 8-10 minutes. Cool slightly.
- Press the remaining dough firmly into the prepared pan. Spread the filling evenly on top, then crumble the reserved dough over the filling.
- Bake for 45-50 minutes until golden and bubbling. Cool completely in the pan. Lift out, slice into squares, and serve.
Notes
