Step 1

Preheat the oven to 375 degrees Fahrenheit. Line a 9x13-inch baking pan with parchment paper. Leave an overhang on the sides to act as handles when removing the bars later.

Step 2

In a large bowl, whisk together the flour, sugar, baking powder, and salt. Using a pastry cutter or with fingers, cut in the cold butter until the mixture resembles coarse crumbs. Mix in the egg and vanilla until the dough starts to clump together.

Step 3

Press about 2/3 of the dough evenly into the bottom of the prepared pan to form the crust. Place the crust in the freezer while preparing the filling.

Step 4

In a separate bowl, combine the blueberries, sugar, cornstarch, lemon juice, and zest. Gently toss to coat the berries. Spread the blueberry mixture evenly over the crust.

Step 5

Crumble the remaining dough over the blueberry layer to form the topping.

Step 6

Bake for 45 to 50 minutes. (Or until the top is lightly golden brown and the blueberry filling bubbles around the edges.)

Step 7

Cool the bars completely in the pan before lifting them out and cutting them into squares. Serve and enjoy!