Blueberry Crumble Bars

These Blueberry Crumble Bars are made with a buttery crumb crust, a sweet blueberry filling, and a golden crumble topping. You can make them with fresh or frozen blueberries, and they are the perfect easy dessert for summer, potlucks, cookouts, or a simple treat with coffee.

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Blueberry Crumble Bars

Blueberry desserts are one of my favorite ways to make something simple feel a little special. These blueberry crumble bars have all the cozy flavor of a blueberry pie, but without rolling out pie dough or making anything too fussy.

The bottom crust and crumble topping come from the same buttery mixture, so the recipe is easy to pull together. The blueberry filling bakes up soft and jammy, with just enough lemon to brighten everything up.

I especially love that these bars can be made with fresh or frozen blueberries. Fresh berries are wonderful when they are in season, but frozen blueberries make this recipe one you can bake any time of year.

If you love easy fruit desserts, my peach crisp is another cozy recipe with that same fruit-and-crumble feel. And if you are in full berry baking mode, my blueberry pie is a classic summer dessert for cookouts and family dinners.

Why You’ll Love This Recipe

• These blueberry crumble bars are easy to make with simple ingredients.
• You can use fresh or frozen blueberries.
• The same mixture is used for the bottom crust and the crumbly topping.
• They are easier than pie but still have that sweet blueberry pie flavor.
• They slice into bars, making them perfect for potlucks, cookouts, lunchboxes, or dessert trays.
• They can be made ahead of time and chilled before serving.

Ingredients

For the Crust and Crumble Topping

• 1 cup unsalted butter, melted
• 1 cup granulated sugar
• 1/2 cup brown sugar
• 2 teaspoons vanilla extract
• 2 3/4 cups all-purpose flour
• 1/2 teaspoon baking powder
• 1/2 teaspoon salt
• 1/2 teaspoon cinnamon, optional

For the Blueberry Filling with Cornstarch

• 4 cups fresh or frozen blueberries
• 1/2 cup granulated sugar
• 3 tablespoons cornstarch
• 1 tablespoon lemon juice
• 1 teaspoon lemon zest, optional
• 1 teaspoon vanilla extract
• Pinch of salt

If You Do Not Have Cornstarch

If you are out of cornstarch, you can use all-purpose flour instead.

For fresh blueberries, use:

• 4 cups fresh blueberries
• 1/2 cup granulated sugar
• 1/4 cup all-purpose flour
• 1 tablespoon lemon juice
• 1 teaspoon lemon zest, optional
• 1 teaspoon vanilla extract
• Pinch of salt

For frozen blueberries, use:

• 4 cups frozen blueberries
• 1/2 cup granulated sugar
• 1/3 cup all-purpose flour
• 1 tablespoon lemon juice
• 1 teaspoon lemon zest, optional
• 1 teaspoon vanilla extract
• Pinch of salt

Fresh vs. Frozen Blueberries

Fresh blueberries work beautifully in this recipe, especially when they are in season. The filling bakes up soft, sweet, and jammy.

Frozen blueberries also work well. Use them straight from the freezer and do not thaw them first. Thawing can make the berries release too much juice before they even go into the oven.

If using frozen blueberries, the bars may need a few extra minutes in the oven. Make sure the filling is bubbling around the edges before removing the pan from the oven. This helps the filling thicken properly as it cools.

Why Add Lemon to Blueberry Crumble Bars?

Lemon juice helps balance the sweetness of the blueberries and gives the filling a brighter flavor. Lemon zest is optional, but it is really good with blueberries.

You do not need a lot. Just a tablespoon of lemon juice and a little zest gives the bars a fresh flavor without making them taste overly lemony.

How to Make Blueberry Crumble Bars

Preheat the oven to 350°F. Grease a 9×13 baking dish or line it with parchment paper. Parchment paper makes it easier to lift the bars out of the pan once they are cooled.

In a large mixing bowl, stir together the melted butter, granulated sugar, brown sugar, and vanilla extract.

Add the flour, baking powder, salt, and cinnamon if using. Stir until the mixture forms soft crumbs. It should look like damp crumbs and hold together slightly when pressed.

Press about two-thirds of the crumble mixture into the bottom of the prepared baking dish. Press it firmly so it creates a sturdy crust.

In a separate bowl, gently stir together the blueberries, sugar, thickener, lemon juice, lemon zest if using, vanilla extract, and salt.

Spread the blueberry filling evenly over the crust.

Sprinkle the remaining crumble mixture over the top.

Bake at 350°F for 45 to 50 minutes if using fresh blueberries, or 50 to 55 minutes if using frozen blueberries. The topping should be lightly golden and the blueberry filling should be bubbling around the edges.

Let the bars cool completely before slicing. For the cleanest slices, chill the pan for about an hour after the bars have cooled to room temperature.

If you like desserts that give you that homemade pie flavor without rolling dough, these bars are a great option. For a traditional pie recipe, you can also try my how to make the perfect pie crust post.

Helpful Tools for Making Blueberry Crumble Bars

Below are a few helpful tools I like for making this recipe. This section may contain affiliate links.

• 9×13 Baking Dish: The right size for these crumble bars and gives the crust, filling, and topping an even bake.
• Parchment Paper: Makes it easier to lift the cooled bars out of the pan for slicing.
• Mixing Bowls: You will need one bowl for the crumble mixture and one for the blueberry filling.
• Rubber Spatula: Helpful for gently mixing the blueberries without crushing them too much.
• Measuring Cups and Spoons: Useful for measuring the crumble ingredients and filling ingredients.
• Microplane or Zester: Great if you are adding fresh lemon zest.
• Cooling Rack: Helps the bars cool evenly before slicing.
• Sharp Knife or Bench Scraper: Makes it easier to cut clean, even bars.

Tips for the Best Blueberry Crumble Bars

• Do not thaw frozen blueberries before using them.
• Make sure the blueberry filling is bubbling around the edges before removing the bars from the oven.
• Let the bars cool completely before slicing so the filling has time to set.
• Chill the bars before cutting if you want cleaner slices.
• Use parchment paper if you want to lift the whole pan of bars out before slicing.
• If your blueberries are very sweet, 1/2 cup sugar in the filling is plenty.
• If your blueberries are very tart, you can increase the filling sugar to 2/3 cup.

How to Get Clean Slices

The hardest part of this recipe is waiting for the bars to cool, but it really does make a difference.

Let the bars cool completely at room temperature, then refrigerate them for about an hour before slicing. Use the parchment paper to lift the bars from the pan, then cut them with a sharp knife or bench scraper.

For extra neat slices, wipe the knife between cuts.

Can I Make These Ahead of Time?

Yes, blueberry crumble bars are a great make-ahead dessert because they need time to cool before slicing.

You can bake them the day before, let them cool completely, and store them covered in the refrigerator overnight. Slice them right before serving for the cleanest bars.

These are perfect for cookouts, potlucks, holidays, or any time you want dessert ready ahead of time.

How to Store Blueberry Crumble Bars

Store cooled blueberry crumble bars in an airtight container at room temperature for 1 to 2 days.

For longer storage, keep them in the refrigerator for up to 5 days. The bars will firm up more in the fridge, which also makes them easier to slice and serve.

Can You Freeze Blueberry Crumble Bars?

Yes, these bars freeze well.

Let the bars cool completely, then slice into squares. Place parchment paper between layers and store them in a freezer-safe container for up to 3 months.

Thaw in the refrigerator or at room temperature before serving.

Can I Use Other Berries?

Yes. This recipe works with several berries.

You can use blackberries, raspberries, black raspberries, or a mixed berry blend. If your berries are extra juicy, add a little extra thickener to help the filling set.

If you have black raspberries, my black raspberry crumble bars are a wonderful garden berry version of this recipe.

More Easy Dessert Recipes

If you loved these blueberry crumble bars, you may also like my peach crisp, blueberry pie, black raspberry crumble bars, apple snickerdoodle bars, and apple cider donut cake.

Frequently Asked Questions

Can I use frozen blueberries?

Yes. Use frozen blueberries straight from the freezer. Do not thaw them first. Frozen berries may need a few extra minutes in the oven.

Can I make blueberry crumble bars without cornstarch?

Yes. You can use all-purpose flour instead of cornstarch. Use 1/4 cup flour for fresh blueberries or 1/3 cup flour for frozen blueberries.

Why are my blueberry crumble bars runny?

The bars may need more baking time, more cooling time, or a little more thickener. Make sure the filling is bubbling around the edges before removing the pan from the oven. Let the bars cool completely before slicing.

Do blueberry crumble bars need to be refrigerated?

They can sit at room temperature for 1 to 2 days, but I prefer storing them in the refrigerator. The filling firms up and the bars slice better when chilled.

Can I add oats to the crumble topping?

Yes. You can add 1/2 cup old-fashioned oats to the crumble mixture for a more rustic topping. If adding oats, reduce the flour by about 1/4 cup.

Can I use blackberries instead of blueberries?

Yes. Blackberries work well in this recipe. If they are large, you can cut some of them in half so the filling spreads more evenly.

Blueberry Crumble Bars

These Blueberry Crumble Bars are made with a buttery crumb crust, a sweet blueberry filling, and a golden crumble topping. Use fresh or frozen blueberries for an easy 9×13 dessert that is perfect for summer, potlucks, cookouts, or make-ahead baking.

Print Recipe Pin Recipe

Prep Time 15 minutes mins

Cook Time 45 minutes mins

Cooling Time 1 hour hr

Total Time 2 hours hrs

Servings: 24 servings

Course: Dessert

Cuisine: American

Ingredients Equipment Method Notes

Ingredients

  

Crust and Crumble Topping

• 1 cup unsalted butter melted
• 1 cup granulated sugar
• 1/2 cup brown sugar
• 2 teaspoons vanilla extract
• 2 3/4 cups all-purpose flour
• 1/2 teaspoon baking powder
• 1/2 teaspoon salt
• 1/2 teaspoon cinnamon optional

Blueberry Filling with Cornstarch

• 4 cups fresh or frozen blueberries
• 1/2 cup granulated sugar
• 3 tablespoons cornstarch
• 1 tablespoon lemon juice
• 1 teaspoon lemon zest optional
• 1 teaspoon vanilla extract
• Pinch of salt

Equipment

• 9×13 baking dish
• Parchment paper, optional
• Large mixing bowl
• Medium mixing bowl
• Measuring cups and spoons
• Rubber spatula
• Cooling rack
• Sharp knife or bench scraper

Method

 

1. Preheat the oven to 350°F. Grease a 9×13 baking dish or line it with parchment paper.
2. In a large bowl, stir together the melted butter, granulated sugar, brown sugar, and vanilla extract.
3. Add the flour, baking powder, salt, and cinnamon. Stir until the mixture forms soft crumbs.
4. Press about two-thirds of the crumble mixture firmly into the bottom of the prepared baking dish.
5. In a separate bowl, gently stir together the blueberries, sugar, cornstarch, lemon juice, lemon zest if using, vanilla extract, and salt.
6. Spread the blueberry filling evenly over the crust.
7. Sprinkle the remaining crumble mixture over the top.
8. Bake for 45 to 50 minutes if using fresh blueberries, or 50 to 55 minutes if using frozen blueberries. The topping should be lightly golden and the blueberry filling should be bubbling around the edges.
9. Cool completely before slicing. For cleaner slices, chill the bars for about an hour before cutting.

Notes

• Use frozen blueberries straight from the freezer. Do not thaw them first.
• If you do not have cornstarch, use all-purpose flour instead. Use 1/4 cup flour for fresh blueberries or 1/3 cup flour for frozen blueberries.
• The bars need to cool completely before slicing so the filling can set.
• Chilling the bars before cutting will give you cleaner slices.
• If your blueberries are very tart, increase the filling sugar to 2/3 cup.
• If adding 1/2 cup old-fashioned oats to the crumble mixture, reduce the flour by about 1/4 cup.
• Blackberries, raspberries, or mixed berries can also be used.