In a medium sized bowl, mix the flour, powdered sugar, cornstarch, and salt together. Use a cheese grater to grate the frozen butter into the dry ingredients. Toss the ingredients together and use your fingers to rub the grated frozen butter into the mixture.
Line a 9x13 pan with aluminum foil and spray lightly with cooking spray. Add the crust mixture into the pan and press firmly into a even ¼ inch layer on the bottom, with ½ an inch extending up the sides of the pan. Refrigerate for 30 minutes.
After the crust has been refrigerated, bake for 20 minutes at 350° F, until it is golden brown.