Blueberry Crumble Bars are the kind of dessert that feels effortless but special. They’re buttery, jammy, and just the right amount of crumbly—perfect for picnics, bake sales, or a cozy afternoon snack. You get a tender crust, a juicy blueberry center, and a golden, crunchy top in every bite.
The best part? They’re easy to make with pantry staples and fresh or frozen berries. If you like desserts that taste homemade without fuss, this one’s a keeper.
Why This Recipe Works
- One dough, two jobs: The same mixture forms the base and the crumble topping, which keeps things simple and consistent in flavor.
- Balanced sweetness: A touch of sugar in the crust and just enough in the filling lets the blueberries shine without being overly sweet.
- Juicy but sliceable: Cornstarch thickens the blueberry layer so the bars hold their shape while staying soft and jammy.
- Great with fresh or frozen berries: No need to wait for peak season—this recipe works year-round.
- Easy to scale and share: The bars bake in a standard pan and cut cleanly once cooled, making them perfect for gatherings.
Ingredients
- For the crust and crumble:
- 1 cup (2 sticks) unsalted butter, melted and slightly cooled
- 1 cup granulated sugar
- 1/2 cup lightly packed brown sugar
- 1 teaspoon vanilla extract
- 1/2 teaspoon almond extract (optional, but lovely)
- 1/2 teaspoon fine salt
- 2 3/4 cups all-purpose flour
- 1/2 teaspoon ground cinnamon (optional)
- Zest of 1 lemon (optional, but brightens the flavor)
- For the blueberry filling:
- 4 cups blueberries (fresh or frozen; if frozen, do not thaw)
- 1/2 cup granulated sugar
- 2 tablespoons cornstarch
- 1 tablespoon lemon juice
- 1 teaspoon lemon zest
- Pinch of salt
- To finish (optional):
- Powdered sugar for dusting
- Vanilla ice cream or whipped cream for serving
Instructions
- Preheat your oven to 350°F (175°C).
Line a 9×13-inch baking pan with parchment paper, leaving overhang on the long sides for easy lifting. Lightly grease the parchment.
- Make the crust/crumble mixture: In a large bowl, whisk the melted butter, granulated sugar, and brown sugar until glossy. Stir in vanilla, almond extract (if using), salt, cinnamon (if using), and lemon zest.
- Add the flour to the bowl and mix with a spatula until large crumbles form and no dry flour remains.
The mixture should look sandy but hold together when pressed.
- Press about two-thirds of the mixture firmly and evenly into the prepared pan to form the base. Use the bottom of a measuring cup to compact it. Set the remaining third aside for the topping.
- Make the blueberry filling: In a medium bowl, toss blueberries with sugar, cornstarch, lemon juice, lemon zest, and a pinch of salt until evenly coated.
- Spread the blueberry mixture over the crust in an even layer.
If using frozen berries, scatter them evenly and pour any remaining sugar-cornstarch mixture over the top.
- Crumble the reserved dough over the blueberries, squeezing some of it into larger clumps for texture. Aim for a mix of small and big pieces to create a rustic top.
- Bake for 40–50 minutes, until the top is golden and the blueberry filling is bubbling around the edges. If the top is browning too quickly, tent loosely with foil for the last 10 minutes.
- Cool completely in the pan on a rack, at least 2 hours.
This helps the filling set so the bars slice cleanly. For sharp edges, chill for 30 minutes before cutting.
- Lift the bars out using the parchment overhang. Cut into 16–24 squares, depending on the size you prefer.
Dust with powdered sugar if you like and serve.
Storage Instructions
- Room temperature: Store in an airtight container for up to 2 days.
- Refrigerator: Keeps well for 4–5 days. The crust stays firm and the filling remains bright.
- Freezer: Freeze cut bars on a sheet pan until solid, then transfer to a freezer bag for up to 2 months. Thaw at room temperature, or warm briefly in a 300°F oven to refresh the crumble.
Health Benefits
- Blueberries are antioxidant-rich: They provide polyphenols and vitamin C, which support overall health and may reduce oxidative stress.
- Fiber content: Blueberries and a hearty crumble offer some fiber, which supports digestion and helps you feel satisfied.
- Balance is key: While these are a treat, using real fruit adds nutrients and natural sweetness, making it a more wholesome dessert option than many frosted or heavily processed choices.
- Easy to adjust: You can lower sugar slightly or swap part of the flour for whole wheat to boost nutrition without losing the core texture.
Common Mistakes to Avoid
- Skipping the cornstarch: Without a thickener, the filling can run and make the crust soggy.
Don’t omit it, especially if using frozen berries.
- Not compacting the base: If the crust isn’t pressed firmly, it can crumble too much when you cut the bars.
- Cutting too soon: Warm bars will fall apart. Cool completely before slicing for neat squares.
- Overbaking: The bars should be golden with bubbling fruit at the edges. Overbaking can dry out the crumble and dull the berry flavor.
- Using too much flour in the crumble: Measure accurately.
Extra flour makes the topping dry and powdery instead of crisp and buttery.
Variations You Can Try
- Oat crumble: Swap 3/4 cup of the flour for rolled oats for a heartier, bakery-style top.
- Whole wheat twist: Replace 1 cup of all-purpose flour with white whole wheat flour for a nutty note.
- Mixed berries: Use a blend of blueberries, raspberries, and blackberries. Keep the total fruit to 4 cups.
- Lemon poppy seed: Add 1 tablespoon poppy seeds to the crust and extra lemon zest for a bright, speckled look.
- Almond crunch: Fold 1/2 cup sliced almonds into the crumble topping and use almond extract for a fragrant finish.
- Gluten-free: Use a quality 1:1 gluten-free flour blend. Check your cornstarch and flavorings for GF certification.
- Reduced sugar: Cut sugar in both the crumble and filling by 2–3 tablespoons each.
The bars will be slightly less sweet but still delicious.
FAQ
Can I use frozen blueberries?
Yes, frozen blueberries work wonderfully. Do not thaw them. Toss with sugar and cornstarch as directed and bake until the filling bubbles at the edges.
How do I know when the bars are done?
Look for a golden top and visible bubbling around the edges.
This means the cornstarch has activated and the filling has thickened.
Can I make these ahead?
Absolutely. Bake the bars the day before, cool completely, and store covered at room temperature. For longer storage, refrigerate and bring to room temp before serving.
What can I use instead of cornstarch?
You can use 3 tablespoons of tapioca starch or 4 tablespoons of all-purpose flour.
Cornstarch gives the cleanest, clearest set.
How do I get clean slices?
Let the bars cool fully, then chill for 30 minutes. Use a sharp knife, wiping the blade between cuts. The parchment sling helps lift them out neatly.
Can I halve the recipe?
Yes.
Use an 8×8-inch pan and reduce the baking time to about 30–38 minutes, watching for the same golden, bubbling cues.
Why is my crumble dry and sandy?
It likely has too much flour or the butter cooled too much. Measure carefully and mix until the dough clumps when pressed.
Wrapping Up
Blueberry Crumble Bars deliver that perfect mix of buttery crunch and juicy fruit, without any complicated steps. They’re easy to bake, easy to share, and always a hit with both kids and adults.
Keep a bag of blueberries on hand, and you’ll have a crowd-pleasing treat ready anytime. Serve them plain, dusted with sugar, or warm with ice cream—there’s no wrong move here.
Blueberry Crumble Bars - A Simple, Buttery Treat With Bright Berry Flavor
Ingredients
- For the crust and crumble: 1 cup (2 sticks) unsalted butter, melted and slightly cooled
- 1 cup granulated sugar
- 1/2 cup lightly packed brown sugar
- 1 teaspoon vanilla extract
- 1/2 teaspoon almond extract (optional, but lovely)
- 1/2 teaspoon fine salt
- 2 3/4 cups all-purpose flour
- 1/2 teaspoon ground cinnamon (optional)
- Zest of 1 lemon (optional, but brightens the flavor)
- For the blueberry filling: 4 cups blueberries (fresh or frozen; if frozen, do not thaw)
- 1/2 cup granulated sugar
- 2 tablespoons cornstarch
- 1 tablespoon lemon juice
- 1 teaspoon lemon zest
- Pinch of salt
- To finish (optional): Powdered sugar for dusting
- Vanilla ice cream or whipped cream for serving
Instructions
- Preheat your oven to 350°F (175°C). Line a 9x13-inch baking pan with parchment paper, leaving overhang on the long sides for easy lifting. Lightly grease the parchment.
- Make the crust/crumble mixture: In a large bowl, whisk the melted butter, granulated sugar, and brown sugar until glossy. Stir in vanilla, almond extract (if using), salt, cinnamon (if using), and lemon zest.
- Add the flour to the bowl and mix with a spatula until large crumbles form and no dry flour remains. The mixture should look sandy but hold together when pressed.
- Press about two-thirds of the mixture firmly and evenly into the prepared pan to form the base. Use the bottom of a measuring cup to compact it. Set the remaining third aside for the topping.
- Make the blueberry filling: In a medium bowl, toss blueberries with sugar, cornstarch, lemon juice, lemon zest, and a pinch of salt until evenly coated.
- Spread the blueberry mixture over the crust in an even layer. If using frozen berries, scatter them evenly and pour any remaining sugar-cornstarch mixture over the top.
- Crumble the reserved dough over the blueberries, squeezing some of it into larger clumps for texture. Aim for a mix of small and big pieces to create a rustic top.
- Bake for 40–50 minutes, until the top is golden and the blueberry filling is bubbling around the edges. If the top is browning too quickly, tent loosely with foil for the last 10 minutes.
- Cool completely in the pan on a rack, at least 2 hours. This helps the filling set so the bars slice cleanly. For sharp edges, chill for 30 minutes before cutting.
- Lift the bars out using the parchment overhang. Cut into 16–24 squares, depending on the size you prefer. Dust with powdered sugar if you like and serve.
Looking for more ideas?
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If you’re craving new flavors, take a look at our World Cuisine category.
If you want something lighter but still satisfying, visit our Healthy & Light category.
If you’re in the mood for a treat, find something sweet in our Sweets & Desserts category.
If you like to plan ahead, get inspired in our Meal Prep & Planning category.
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