Step 1 Heat the oven to 350 degrees.
Step 2 In the bowl of a stand mixer, or in a large bowl using an electric mixer, cream together the butter and brown sugar until smooth. Add the flour and mix well.
Step 3Place the mixture in a parchment-lined 13-by-9-by-2-inch baking pan, pressing the mixture firmly onto the base of the pan to form a packed, even layer.
Step 4Bake the crust until lightly golden, about 20 to 25 minutes. Set aside until cool.