How to Make It
In the bowl of a stand mixer fitted with the paddle, cream the butter with the sugars at medium speed for 2 minutes. With the mixer at low speed, beat in the sifted flour-and-salt mixture.
Preheat the oven to 350°. Line a 9-by-13-inch baking pan with parchment paper, allowing 2 inches of overhang on the 2 long sides. Transfer the dough to the pan and press it over the bottom and 1 1/4 inches up the side all around. (You can cover the dough with plastic wrap and press with the bottom of a measuring cup.) Be sure the corners are not too thick. Refrigerate until firm.
Bake the crust for 30 to 35 minutes, until golden brown; halfway through baking, use the back of a spoon to smooth the sides and corners of the crust. Transfer the pan to a wire rack and let the crust cool before filling.