Preheat your oven to 350°F (177°C). Line a 9-inch square baking pan with parchment paper, leaving an overhang on the sides to easily lift the bars out later.
Step 2: Make the Crust
Combine Ingredients: In a medium bowl, mix the flour, 1 cup oats, brown sugar, baking powder, lemon zest, cinnamon, and salt.
Add Butter: Pour the melted butter into the dry ingredients and mix until the mixture becomes crumbly.
Press and Bake: Press 2/3 of the mixture into the prepared pan to form the crust. Bake for 10 minutes until it starts to set.
Step 3: Prepare the Filling
Cook Blueberries: In a saucepan, combine the blueberries, granulated sugar, cornstarch, and lemon juice. Cook over medium heat for 2-3 minutes until the sugar dissolves and the mixture thickens.
Add Zest: Remove from heat and stir in the lemon zest for an added burst of flavor.
Step 4: Assemble and Bake
Spread Filling: Evenly spread the blueberry filling over the pre-baked crust.
Add Topping: Stir the remaining 2 tablespoons of oats into the reserved crumble mixture and sprinkle it over the blueberry filling. Press lightly to ensure it adheres.
Bake: Return the pan to the oven and bake for 45-55 minutes, or until the top is lightly browned and the filling is bubbling.
Step 5: Cool and Serve
Cool Completely: Let the bars cool completely on a wire rack. Use the parchment paper overhang to lift the bars out of the pan and cut them into squares.
Valuable Tips for Seamless Cooking
Helpful Tip: Use Fresh Blueberries
While fresh blueberries provide the best flavor, you can use frozen blueberries if fresh ones are not available. Just be sure to thaw and drain them before using.
Helpful Tip: Prevent Soggy Crust
Bake the crust until it starts to set before adding the filling to prevent it from becoming soggy.
Helpful Tip: Customize the Topping
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