Ingredients
Crust & Topping
- 1 1/2 cups all-purpose flour
- 1 1/2 cups old fashioned rolled oats
- 3/4 cups light brown sugar
- 1/2 teaspoon cinnamon
- 1/2 teaspoon kosher salt
- 1 cup cold butter, cubed (2 sticks)
Filling
- 1/2 cup granulated sugar
- 3 tablespoons cornstarch
- 2 1/2 cups blueberries
- 1 tablespoon lemon juice
- 1 teaspoon lemon zest
Instructions
- Prepare Pan: Line a 9×9-inch pan with parchment paper and coat with nonstick spray to prevent sticking. Set aside.
- Make Crust & Topping Mixture: In a large bowl, whisk together flour, oats, brown sugar, cinnamon, and salt. Add cold, cubed butter and use a pastry blender to cut the butter into the dry ingredients until the mixture resembles very coarse sand.
- Form Crust: Divide the mixture in half. Press half firmly into the bottom of the prepared pan to create an even crust layer. Reserve the remaining half for the crumble topping.
- Prepare Filling: In another large bowl, whisk together granulated sugar and cornstarch. Gently fold in the blueberries, coating them evenly. Add lemon juice and zest, stirring delicately to combine without crushing the berries.
- Assemble Bars: Spread the blueberry mixture evenly over the crust in the pan. Sprinkle the reserved crumble mixture evenly over the blueberry layer and lightly press it down.
- Chill: Refrigerate the assembled bars for 30 minutes to help them set before baking.
- Bake: Preheat the oven to 350°F (175°C). Bake the bars for 35 to 40 minutes until the fruit begins to bubble and the crumble topping is golden brown.
- Cool and Serve: Remove from the oven and allow bars to cool completely before cutting into 16 squares for serving.
Notes
- Ensure butter is cold when cutting into the flour mixture for the best crumbly texture.
- Use fresh or frozen blueberries; if using frozen, do not thaw before mixing.
- Line the pan with parchment paper to make removal easier and simplify cleanup.
- Bars can be stored in an airtight container at room temperature for up to 3 days or refrigerated for up to a week.
- Optional: sprinkle a little coarse sugar over the topping before baking for extra crunch.
- Prep Time: 15 minutes
- Cook Time: 40 minutes
- Category: Dessert
- Method: Baking
- Cuisine: American