These popular butter cookies are cooled and decorated and then stacked to form wedding-cake shapes.
Place the flour, cornstarch, and sugar in the bowl of a food processor fitted with the blade attachment, and pulse to mix. Add the butter, and pulse until mixture resembles a coarse meal. Transfer the dough to a lightly floured work surface, and knead until dough is smooth and uniform, about 1 minute.
Heat oven to 300 degrees. Line 2 baking sheets with parchment paper; set aside. Roll the dough 1/2 inch thick. Using 3-inch, 2 1/4-inch, 1 3/4-inch, 1 1/4-inch, and 1-inch round cookie cutters, cut out 5 cookies of each size. Place rounds 1 inch apart on the prepared baking sheets, and place in the oven. Bake until light golden, about 1 hour. Transfer to wire racks to cool. Reroll scraps of dough and repeat process, cutting out 3 cookies of each size. When cookies have completely cooled, decorate, and stack to form wedding-cake shapes.