Preheat oven to 325°F (160°C). Line a baking sheet with parchment paper.

Beat butter and sugar with a hand mixer until smooth and pale, about 2 minutes.

Add flour and mix on low until a crumbly dough forms, then press together by hand into a smooth ball.

Scoop tablespoon sized dough balls, roll in extra sugar if desired, place 2 inches apart on sheet, and flatten to 1/4 inch thick using a fork or glass.

Bake until edges are barely golden, 12 to 14 minutes. Let cool on the pan for 5 minutes, then transfer to a wire rack.