2 sticks, plus 2 tablespoons regular (salted) butter, softened
1 cup sugar
2 cups all-purpose flour
Scant 1 cup corn starch
Preheat oven to 325 degrees.
Cream butter and sugar together. Sift in flour and cornstarch and blend together using a pastry cutter until the ingredients all come together. (If mixture seems excessively dry, cut in 1 more tablespoon of butter—but only if you really need it.
Form dough into a ball, wrap in plastic wrap, and refrigerate 20 minutes.
Roll onto a lightly floured surface and cut into rounds. Place on a cookie sheet lined with parchment paper or a baking mat.
Bake for 20 minutes. Do not allow shortbread to brown; the edges should have the faintest golden tinge.