Preheat your oven to 350°F and grease an 8x8-inch baking pan. Line it with parchment paper for easy removal. In a medium bowl, mix the flour, softened butter, and granulated sugar until crumbly. Press the mixture evenly into the bottom of the prepared pan. Bake the crust for 15-18 minutes or until lightly golden. Let it cool while you prepare the filling.