These lemon blueberry crumble bars are naturally sweetened and feature a tender almond flour crust paired with a bright, cooked blueberry filling. The filling is simmered until thick, poured over a par-baked crust, then topped with the remaining crumble and baked briefly. Finish with fresh lemon zest for a refreshing summer dessert that’s both satisfying and made from whole ingredients.
This recipe is a long-time favorite because it’s simple, naturally sweetened, and versatile. It balances the nutty almond crust with the sweet-tart blueberry filling and a hit of lemon zest on top.
What You Need for Blueberry Crumble Bars
8×8-inch pan: These bars are formulated for an 8×8-inch pan. Using a different size will change thickness and texture—too small will make overly thick bars and too large will make them too thin to hold together.
Fine almond flour (superfine or blanched): Choose superfine or blanched almond flour for the best texture. Coarser almond meal will yield a grainier crust and is not recommended for this recipe.
Fresh blueberries: Fresh berries are preferred for the best texture and flavor. If using frozen, thaw completely, drain excess liquid, and be sure to cook them down until thick.
Tapioca flour: Tapioca flour (also called tapioca starch) is used to thicken the blueberry filling and help it set cleanly inside the bars.
Variations and Substitutions
Swap in other berries—strawberries, raspberries, or blackberries work well—just be sure to cook them down until the filling thickens. We do not recommend replacing the almond flour with another grain-free or wheat-based flour unless you are experienced with texture adjustments; the almond flour provides both flavor and structure unique to this recipe.
Lemon Blueberry Crumble Bars
These bars are gluten-free and made with wholesome ingredients. The bright lemon and sweet blueberries make them perfect for summer parties, potlucks, or simple weeknight treats.
Ingredients
For the Crust and Crumble
- 3 cups superfine (blanched) almond flour
- 1 cup rolled oats
- 2 tablespoons milk (any kind)
- 1/4 cup coconut oil, room temperature
- 1/4 cup honey or maple syrup
- 1 teaspoon vanilla extract
- 1/8 teaspoon salt
For the Berry Filling
- 3 cups fresh blueberries
- 1/2 cup water
- 1/4 cup lemon juice
- Zest from one lemon
- 1/4 cup honey or maple syrup
- 2 tablespoons tapioca flour (tapioca starch)
- Pinch of salt
Instructions
- Preheat the oven to 350°F (175°C). Spray an 8×8-inch pan with coconut oil or line it with parchment paper and set aside.
- In a medium-to-large mixing bowl, combine all crust and crumble ingredients until evenly mixed.
- Reserve about one-third of the mixture for the crumble topping. Press the remaining two-thirds firmly and evenly into the bottom of the prepared 8×8 pan.
- Bake the crust at 350°F for 10 minutes. Remove from the oven and let the crust cool while you prepare the filling.
- For the filling, combine the blueberries, water, lemon juice, lemon zest, honey or maple syrup, tapioca flour, and a pinch of salt in a medium saucepan. Bring to a boil over medium-high heat, breaking up the berries with a spoon as they soften. Once boiling, reduce heat and simmer for 10–15 minutes, stirring frequently, until the mixture thickens to a jam-like consistency.
- Pour the hot blueberry filling over the cooled crust and spread it evenly. Sprinkle the reserved crumble mixture over the top.
- Return the pan to the oven and bake for another 10 minutes at 350°F, just until the topping is set.
- Remove from the oven and cool for about 20 minutes on a rack. For best results, chill in the refrigerator for at least 2 hours to allow the filling to fully set before slicing into bars.
- Slice into nine bars and garnish each with additional lemon zest if desired. Serve chilled or at room temperature.
Tips & Notes
- Let the almond flour crust cool before adding the blueberry filling to avoid a soggy base.
- Honey, maple syrup, or agave all work as natural sweeteners—choose based on flavor preference.
- Do not cut the bars while still warm; they need time to set in the refrigerator. Cutting too early will cause them to fall apart.
- If using frozen blueberries, thaw and drain them first, then simmer until the excess moisture cooks off and the filling thickens.
Storage
Room Temperature
If you will eat the bars within 1–2 days, store them in an airtight container at room temperature. Make sure they are completely cooled before sealing to prevent condensation.
Refrigerator
Store in an airtight container for 3–4 days. Serve chilled or bring to room temperature for about 30 minutes before eating.
Freezer
For longer storage, wrap individual bars tightly in plastic wrap or parchment and place them in a freezer-safe container separated by parchment paper. Freeze for up to 2–3 months. Thaw overnight in the refrigerator or at room temperature for a few hours. Reheat briefly in a low oven if you prefer them warm.
Serving Variations
- À la Mode: Serve warm bars with vanilla ice cream or a dollop of whipped cream for contrast in temperature and texture.
- Lemon Glaze: Drizzle a simple lemon glaze (powdered sugar mixed with a bit of fresh lemon juice) over cooled bars for extra brightness.
- Breakfast Parfait: Crumble bars into layers with Greek yogurt and fresh blueberries for a hearty parfait.
- Brunch Dessert: Offer bars on a brunch platter alongside fresh fruit and pastries for a crowd-pleasing sweet option.
FAQ
Can I use frozen blueberries instead of fresh?
Yes. Thaw them, drain excess liquid, and cook the filling a little longer to evaporate extra moisture so the filling will set properly.
Can I substitute lemon zest with lemon juice?
Lemon zest gives the most concentrated lemon flavor. You can use more lemon juice if needed, but reduce other liquids slightly so the filling doesn’t become too watery.
Can I make these bars in advance?
Absolutely. Make them a day ahead and chill in the refrigerator so they slice cleanly. They also freeze well for longer storage.
Can I add nuts to the crumble topping?
Yes—chopped almonds, walnuts, or pecans add a pleasant crunch. Fold them into the reserved crumble mixture before topping the bars.
Nutrition
Approximate per-bar values (may vary): Calories: 396 kcal; Carbohydrates: 39 g; Protein: 10 g; Fat: 26 g; Fiber: 7 g; Sugar: 22 g. Use these numbers as an estimate only.
If you enjoy this recipe, try experimenting with other berry mixtures or small additions like a sprinkle of toasted nuts on top. These lemon blueberry crumble bars are a reliable, crowd-pleasing recipe that balances bright citrus and juicy berries with a satisfying, nutty crumble.