Blueberries are a summertime favorite, and make these delicious bars perfectly tart!

Instructions:

1. Preheat the oven to 350 degrees F. Spray a 9 x 13-inch baking dish with cooking spray, or brush with butter.
2. In the bowl of a stand mixer, or in a large bowl using an electric hand mixer, cream together the butter, brown sugar, and granulated sugar. Add the egg and vanilla and combine. Stir in the flour, oats, salt, and baking powder until incorporated. In a medium bowl, stir together the blueberries, lemon juice, sugar, and tapioca and set aside.
3. Press half of the crumble mixture into the bottom of the prepared pan. Spread the blueberry mixture evenly over the crust. Gently crumble the remaining crust mixture over the blueberries. Bake for 45–50 minutes, until lightly golden brown. Cool completely before cutting into bars.