American Flag Cookie Cake

Preheat the oven to 400 °F. In a large bowl, whisk together the flour and brown sugar. Cut the butter into pieces, and using two forks or your fingers, work the butter into the flour mixture until it's the consistency of wet sand. Press the cookie dough firmly and evenly into a non-stick quarter size (9x13 inches) rimmed baking sheet. Bake the shortbread for 10 to 15 minutes until it is pale golden. Remove the shortbread from the oven, place it on a cooling rack and allow it to cool completely while still in the pan. Once it has cooled, use a sharp knife to carefully cut around the edges then invert the shortbread cookie onto your serving platter.