These best blueberry crumb bars have a crunchy crust, plenty of gooey blueberry pie filling, and a buttery crumble topping! You can use fresh blueberries or frozen blueberries to make the blueberry mixture.

Blueberry Crumble Bars

It’s no secret that I absolutely love baking with blueberries! And these delicious blueberry crumb bars might just be my favorite blueberry recipe yet. The flavors and textures are simply out of this world. They’re essentially a blueberry pie/blueberry crisp hybrid.

Cut into squares and topped with ice cream, these are the ultimate crowd-pleasing dessert treat. And yes: serving them with ice cream is an absolute must! Are they delicious without it? Of course… but they’re a million times better when you top that crumb topping with a giant scoop of vanilla.

Ingredients for Blueberry Crumble Bars

• Butter: Be sure to use butter that’s been brought to room temperature. Butter that’s too cold won’t evenly incorporate into the mixture. I suggest unsalted butter, but in a pinch, salted will work. Simply omit the salt called for.
• Sugar: For the best flavor, granulated sugar and brown sugar are used. However, in a pinch, all granulated sugar will work fine. I don’t suggest using all brown sugar.
• All-Purpose Flour: I don’t suggest using any flour substitutes! But if you’re going to experiment, your best bet is a 1-for-1 GF flour. Nut flours will not work in this recipe.
• Salt: A small amount of salt both cuts the sweetness and helps enhance all of the other flavors in this recipe. Fine sea salt works great, but regular table salt will also work fine.
• Egg: Be sure to use a large egg and bring it to room temperature before adding it to the batter.
• Sour Cream:
• Lemon: You’ll use both the lemon juice and the lemon zest in this recipe. Surprisingly, the bars do not have an intense lemon flavor. Instead, it enhances the blueberry flavor and it gives it a pop of freshness.
• Cornstarch: In addition to flour, cornstarch helps thicken the custard filling.
• Cinnamon: A tiny dash enhances the blueberry flavor and adds a subtle warmth. You may skip this or use a dash of nutmeg instead.
• Vanilla Extract: Vanilla adds sweetness and enhances all of the other flavors in the recipe. Always use pure vanilla extract, and not artificial vanilla.
• Blueberries: Fresh or frozen blueberries work fine in this recipe. If you’re using frozen blueberries, DO NOT thaw them first.

No leavening agents are used in this recipe (baking soda/baking powder). So the blueberry bars bake up dense, buttery, and intensely fruity!

How to Make Them

1. Baking Prep: Preheat the oven and line an 8×8-inch baking pan with parchment paper. Spray the pan with non-stick baking spray and set the prepared pan aside until needed.
2. Make the Crust/Crumb Topping: The crust and crumb topping are one recipe that gets divided. You’ll reserve 1 cup for the crumb topping, and press the rest into the bottom of the prepared pan.
3. Make the Blueberry Filling: In a mixing bowl, combine the egg, sour cream, sugar, cornstarch, lemon, flour, cinnamon, and vanilla. Fold in 1 and 1/2 cups of the blueberries.
4. Assemble the Bars: Pour the filling over the crust, then sprinkle the remaining blueberries on top. Use your hands to scatter the remaining crust over the filling.
5. Bake the Bars: You’ll need to bake for about 1 hour. And then let the bars cool completely in the pan (about another hour) before serving them. Waiting for them to cool and firm up is definitely the hardest part of this recipe!
6. Slice and Serve: Use the parchment paper to help you remove the bars from the pan. Cut into squares and serve with ice cream!

You can wrap any leftovers in Saran Wrap and store in the fridge for up to 3 days!

Tools for this Recipe

• 8×8-Inch Baking Pan
• Parchment Paper
• Nonstick Baking Spray
• Mixing Bowl
• Electric Hand Mixer
• Large Knife

More Crumb Bars:

• Apple Crumb Bars
• Cranberry Crumb Bars
• Raspberry Crumb Bars
• Brown Butter Cherry Crumb Bars