Preheat oven to 300°F (150°C) and line a baking sheet with parchment. In a stand mixer with the paddle attachment, beat the butter on medium until smooth. Slowly add the powdered sugar, then whip on medium-high for 5 full minutes, scraping the bowl once.

With the mixer on low, mix in the flour just until the dough comes together and pulls away from the bowl, about 30 sec to 1 min. Do not overmix.

Scoop tablespoon-sized balls of dough and place them 1 inch apart on the sheet. Dip a fork in sugar or flour and press each ball into a crisscross pattern, flattening to ½ inch.

Bake for 18 to 20 minutes, until bottoms are barely golden and tops remain pale. They will feel soft but will set as they cool.

Dust warm cookies with powdered sugar through a small sieve. Cool completely on the sheet, then serve.