Blueberry Crumb Bars

These blueberry crumb bars are buttery, jammy, and topped with the most irresistible shortbread-style crumble. 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 crumb bars are your favorite kind of easy dessert, my strawberry rhubarb crumb bars are another sweet-tart version to bake, and my fresh lemon crumb bars are a lighter, citrusy option.

Why you'll love this recipe

• One dough, two jobs. The buttery shortbread dough is both the crust and the crumble topping — less prep, fewer dishes.
• They slice beautifully. Once cooled, they hold their shape for clean squares that are perfect for sharing and gifting.
• Fresh or frozen berries. Make them year-round; frozen blueberries go straight in, no thawing.
• Part of a whole crumb bar family. If you love these, you'll love my easy peach crumb bars and apple pie crumb bars for late summer and fall.
• Crowd-pleasing. Just as at home at a picnic or potluck as they are with a cup of coffee — like my fudgy brownie crumb bars.

Ingredients You'll Need

• All-purpose flour: The base of the buttery crust and crumble.
• Granulated sugar: Sweetens both the dough and the filling.
• Unsalted butter: Melted, so the dough presses easily into a crust and crumbles over the top. Salt + vanilla: Round out the shortbread flavor.
• Blueberries: Fresh or frozen both work — add frozen straight from the freezer to avoid excess moisture. They're the same berries I love in my sourdough discard blueberry muffins.
• Lemon juice + zest: Brighten the filling and enhance the blueberry flavor without making it taste lemony.
• Cornstarch: Thickens the filling so the bars set and slice cleanly (tapioca flour works too).

Easy Substitutions & Variations

• Gluten-free: Use a 1:1 gluten-free flour blend.
• Dairy-free: Swap in melted plant-based butter.
• Cornstarch: Tapioca flour works as a 1:1 replacement.
• Frozen berries: Use them straight from the freezer, no thawing.
• Mixed berry: Swap some blueberries for raspberries, blackberries, or strawberries — the same berry mixing I love in my bakery-style banana blackberry muffins.
• Lemon blueberry: Lean into the citrus with extra lemon zest, just like my lemon blueberry cookies.
• Almond crumble: Add ½ teaspoon almond extract to the crumble for a subtle bakery flavor.
• Brown sugar crumble: Replace half the sugar in the dough with brown sugar for a deeper, caramel-like flavor.

Expert Tips

1. Press the crust firmly. A well-packed base holds together and gives you clean slices.
2. Mix the cornstarch into the sugar first. Combining them before adding the berries prevents starchy clumps in the filling.
3. Wait for the center to bubble. The edges will look done before the middle — make sure the center is bubbling so the filling sets.
4. Don't thaw frozen berries. Adding them frozen keeps the filling from getting watery.
5. Cool completely (or chill). Let the bars cool fully before slicing; for extra-neat squares, chill 30–60 minutes first.

The genius of a crumb bar is that one buttery shortbread dough does all the work — you press most of it in for the crust and scatter the rest on top for the crumble. No separate pastry, no rolling, just one bowl. The cornstarch-thickened blueberry filling bakes down jammy and sliceable, with a hit of lemon that makes the berries taste even more like themselves.

If you love blueberries in every form, you'll want to bake my lemon blueberry mascarpone cake too. And for another fruit dessert with the same rustic, jammy charm, my strawberry rhubarb galette is a forever favorite.

Blueberry Crumb Bars FAQ

Blueberry Crumb Bars Troubleshooting Guide

Storage

• Store in an airtight container at room temperature for up to 2 days, or in the refrigerator for up to 5 days.
• Freeze tightly wrapped for up to 2 months; thaw at room temperature before serving.

Other Dessert Bar Recipes to Consider