Preheat your oven to 350° F and prepare a 9 x 13-inch baking pan with cooking spray.
Cream together the powdered sugar and cold butter until light and fluffy. Gradually add in 2 cups of flour, mixing until it resembles cornmeal. Press into the bottom of the prepared pan and bake for 15-20 minutes until golden brown.
In a large bowl, beat together the eggs, granulated sugar, and fresh lemon juice until well combined. Sift in the reserved 1/2 cup of flour and baking powder, mixing thoroughly.
Pour the lemon filling over the baked crust and return to the oven. Bake for an additional 20-25 minutes until the top is lightly browned and the center is set.
Allow the lemon bars to cool completely on a wire rack before dusting with powdered sugar. Cut into squares and serve.