These Blueberry Crumb Bars are buttery, jammy, and topped with the most irresistible shortbread-style crumble topping. Made with simple ingredients and bursting with fresh or frozen blueberries, they’re the kind of easy dessert that feels bakery-worthy but comes together in one bowl.
If you’re looking for a soft, sliceable bar with a gooey blueberry center and crisp crumb topping, this is one you’ll come back to all year long.
Why you'll love this recipe
These bars are simple, cozy, and incredibly versatile. The buttery crust doubles as the crumble topping, which means less prep and fewer dishes.
They also hold their shape beautifully once cooled, making them perfect for slicing, sharing, and even gifting.
If you try these and love them, you should try my peach crumb bars and my apple pie crumb bars! They are perfect for the late summer and fall months.
Best seasons, holidays, and occasions for this recipe
Blueberry crumb bars shine in spring and summer when blueberries are at their peak, but they’re just as delicious year-round using frozen berries.
They’re perfect for picnics, potlucks, baby showers, brunch spreads, or as a simple weeknight dessert.
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Ingredients
- all-purpose flour
- granulated sugar
- unsalted butter
- salt
- vanilla extract
- blueberries
- lemon juice
- lemon zest
- cornstarch
See recipe card for quantities.
Ingredient notes
Blueberries: Fresh or frozen, both work well. If using frozen, don’t thaw! This helps prevent excess moisture.
Lemon juice & zest: Brightens the filling and enhances the blueberry flavor without making it taste lemony.
Cornstarch: Thickens the filling so the bars set properly and slice cleanly. You can also use tapioca flour in its place.
Butter: Melted butter creates a soft, rich crumble that presses easily into a crust.
Four-Step Overview
Note: I bake by weight for accuracy. Cup measurements are approximate and may vary depending on how you scoop.
Step 1: Make the dough: Mix melted butter, sugar, vanilla, salt, and flour into a crumbly dough.
Step 2: Press the crust: Press ⅔ of the crumb dough into the pan to form the base. Pushing firmly is the key!
Step 3: Add the filling: Mix the sugar and cornstarch together separately to prevent the starch from clumping. Toss blueberries with sugar and starch mixture, add lemon juice and zest, then spread over the base.
Step 4: Top & bake: Crumble remaining dough on top and bake for 65-70 minutes or until golden and bubbly (center must be bubbly too!).
Weigh your ingredients! Using a kitchen scale ensures your measurements are accurate, which is key for getting consistent results in baking. It takes the guesswork out of measuring and helps your recipes turn out exactly as intended every time.
Substitutions
Flour: Use a 1:1 gluten-free flour blend.
Butter: Substitute with melted plant-based butter for a dairy-free version.
Blueberries: Use frozen if fresh aren’t in season—no thawing needed.
Cornstarch: I've used tapioca flour in place of the cornstarch and it worked great.
Variations
Mixed Berry: Swap blueberries for a mix of raspberries, blackberries, and strawberries.
Almond Crumble: Add ½ teaspoon almond extract to the crumble for a subtle bakery flavor.
Brown Sugar Crumble: Replace half the sugar with brown sugar for a deeper, caramel-like flavor.
Equipment
- Kitchen scale
- 8x8 baking pan
- Parchment paper
- Mixing bowls
- Rubber spatula
Storage
Store the bars in an airtight container at room temperature for up to 2 days, or in the refrigerator for up to 5 days.
These also freeze well—wrap tightly and freeze for up to 2 months. Thaw at room temperature before serving.
Audrey's Tip
Let them cool completely: It’s tempting to slice these warm, but letting the bars cool fully is what gives you those clean, bakery-style squares. If you want extra neat slices, chill them for 30–60 minutes before cutting.
FAQ
No. use them straight from the freezer to avoid excess moisture.
They likely need more cooling time. The filling sets as it cools.
Yes! Bake in a 9x13 pan and add a few extra minutes to the bake time.
Yes, that should work out just fine. For non-frozen crumb bar fillings (like my peach crumb bars and apple crumb bars), you usually only need to bake them for 40-45 minutes.
Related
Looking for other recipes like this? Try these:
Blueberry Crumb Bars
Equipment
- Kitchen Scale
- 8×8 baking pan
- Parchment Paper
- Mixing bowls
- Rubber spatula
Ingredients
Crust & Crumble
- 240 g all-purpose flour 2 cups
- 200 g granulated sugar 1 cup
- 170 g unsalted butter melted (¾ cup)
- ½ teaspoon salt
- 1 teaspoon vanilla extract
Blueberry Filling
- 300 g blueberries 2 cups, fresh or frozen
- 100 g granulated sugar ½ cup
- 1 tablespoon lemon juice
- 1 teaspoon lemon zest
- 2 tablespoons cornstarch
Instructions
- Prep the pan: Preheat oven to 350°F. Line an 8x8 pan with parchment paper.
- Make the crumble dough: In a bowl, mix melted butter, sugar, vanilla, and salt. Stir in flour until a soft, crumbly dough forms.
- Form the crust: Press about ⅔ of the mixture firmly into the bottom of the pan.
- Make the filling: In a separate bowl, toss blueberries with sugar, lemon juice, zest, and cornstarch until evenly coated.
- Assemble: Spread the blueberry mixture over the crust, then crumble the remaining dough evenly on top.
- Bake: Bake for 65 minutes, until the top is golden and the filling is bubbling in the middle.
- Cool: Let cool completely before slicing.
Notes
Store the bars in an airtight container at room temperature for up to 2 days, or in the refrigerator for up to 5 days.
These also freeze well—wrap tightly and freeze for up to 2 months. Thaw at room temperature before serving. Audrey's tip:
Let them cool completely: It’s tempting to slice these warm, but letting the bars cool fully is what gives you those clean, bakery-style squares. If you want extra neat slices, chill them for 30–60 minutes before cutting. If using fresh berries, you will only need to bake for 40-45 minutes.
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