Blueberry Crumb Bars Recipe

I love making these Blueberry Crumb Bars whenever I have fresh blueberries on hand. They’re buttery, fruity, and the perfect balance of sweet and tart. With a tender shortbread-like base, juicy blueberry filling, and golden crumb topping, they’re simple to make yet look and taste like something from a bakery.

Why You’ll Love This Recipe

I adore this recipe because it’s so easy and versatile. The crust and crumble topping are made from the same dough, so there’s less mixing and cleanup. The blueberry filling is bright and fresh, with a hint of lemon that enhances the berries’ natural flavor. These bars hold together beautifully once cooled, making them perfect for picnics, potlucks, or a cozy weekend treat. I also love that they can be served warm with ice cream or at room temperature with a dusting of powdered sugar.

Ingredients

(Note: All ingredient amounts are listed in the recipe card below.)
3 cups fresh blueberries
1/4 cup (50 g) granulated sugar
1 tablespoon cornstarch
1 tablespoon fresh lemon juice
zest of a lemon, optional (alternatively, add a sprinkle of cinnamon)
3/4 cup (170 g) unsalted butter, room temperature
1/3 cup (66 g) granulated sugar
1/3 cup (66 g) light brown sugar, packed
2 teaspoons vanilla
2 cups (250 g) all-purpose flour, spooned and leveled
1/2 teaspoon baking powder
1/2 teaspoon salt
powdered sugar, for dusting (optional)

Directions

1. I preheat my oven to 350°F (175°C) and line an 8×8-inch or 9×9-inch baking pan with parchment paper, leaving a little overhang for easy removal later.
2. In a medium bowl, I combine the blueberries, 1/4 cup sugar, cornstarch, lemon juice, and lemon zest (or cinnamon if using). I gently toss everything together until the berries are evenly coated, then set the mixture aside.
3. In a large mixing bowl, I beat together the butter, 1/3 cup granulated sugar, 1/3 cup brown sugar, and vanilla until creamy and smooth.
4. I add the flour, baking powder, and salt, and mix until crumbly. The dough should resemble coarse crumbs that hold together when pressed.
5. I press about two-thirds of this crumb mixture evenly into the bottom of the prepared pan to form the crust, pressing it down firmly with my fingertips or the back of a spoon.
6. I spread the blueberry mixture evenly over the crust, making sure the fruit reaches the edges.
7. I sprinkle the remaining crumb mixture evenly over the top, leaving some larger chunks for texture.
8. I bake for about 40–45 minutes, or until the top is lightly golden and the blueberry filling is bubbling around the edges.
9. Once baked, I let the bars cool completely in the pan, then lift them out using the parchment overhang. Once cool, I dust with powdered sugar if desired, then cut into squares.

Servings and Timing

This recipe makes about 9–12 bars, depending on how large I cut them.
Total time: 1 hour, including baking and cooling time.
Active prep time: 15 minutes, baking time: 40–45 minutes.

Variations

• I sometimes swap in raspberries or blackberries for a mixed-berry version.
• For extra crunch, I add 1/4 cup chopped almonds or pecans to the crumble topping.
• If I want a spiced flavor, I use cinnamon and a pinch of nutmeg instead of lemon zest.
• To make them dairy-free, I substitute the butter with a good-quality plant-based alternative.
• I can drizzle a simple lemon glaze over the cooled bars for extra sweetness and shine.

Storage/Reheating

I store the bars in an airtight container at room temperature for up to 2 days, or in the refrigerator for up to 5 days. If refrigerated, I bring them to room temperature before serving so the crumble softens slightly. To warm them, I pop a piece in the microwave for about 10–15 seconds or reheat gently in a low oven (around 300°F) for a few minutes. They can also be frozen for up to 2 months; I wrap individual bars tightly before freezing and thaw them in the fridge overnight.

FAQs

Can I use frozen blueberries instead of fresh?

Yes — I use them straight from the freezer without thawing to avoid excess liquid. I might bake for a few extra minutes if needed.

Can I make these gluten-free?

Yes, I replace the all-purpose flour with a 1:1 gluten-free flour blend. The texture remains very close to the original.

Why is the filling runny?

If the filling is too juicy, it usually means not enough cornstarch or the bars were cut before they fully cooled. Cooling helps the filling set.

Can I double the recipe?

Absolutely. I double all ingredients and bake in a 9×13-inch pan for about 50–55 minutes.

How do I get clean slices?

I let the bars cool completely, then use a sharp knife wiped clean between each cut for neat edges.

Can I add oats to the crumb topping?

Yes — replacing 1/2 cup of the flour with rolled oats gives a heartier, slightly chewy texture.

What’s the best way to serve these?

I love them plain at room temperature, but they’re amazing slightly warm with a scoop of vanilla ice cream or a dollop of whipped cream.

How do I know when they’re done baking?

The top should be lightly golden, and you’ll see some bubbling from the fruit around the edges. The center should no longer look doughy.

Can I make them ahead of time?

Yes, I often make them a day in advance. They actually taste even better the next day as the flavors meld.

Do I need to refrigerate them?

Only if the weather is warm or you plan to keep them for more than 2 days. Otherwise, they keep fine covered at room temperature.

Conclusion

I find these Blueberry Crumb Bars to be one of the easiest, most satisfying desserts to bake. They’re buttery, fruity, and just the right amount of sweet — everything I love in a summer (or anytime) treat. Whether I’m serving them warm with ice cream or cool with coffee, they always bring a burst of blueberry goodness that feels comforting and homemade.

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