- 2 cups all-purpose flour
- 1/2 teaspoon baking powder
- 1/2 teaspoon salt
- 1 1/2 sticks (3/4 cup) unsalted butter, softened
- 1 cup sugar
- 1 large egg
- 1/2 teaspoon vanilla
- Garnish: coarse or sanding sugar; or melted chocolate (see cooks’ note, below)
- Whisk together flour, baking powder, and salt in a small bowl.
- Beat together butter and sugar in a large bowl with an electric mixer at medium-high speed until pale and fluffy, about 3 minutes in a standing mixer (preferably fitted with paddle attachment) or 6 with a handheld. Beat in egg and vanilla. Reduce speed to low, then add flour mixture and mix until just combined.
- Form dough into a 12-inch log (2 inches in diameter) on a sheet of plastic wrap and roll up dough in plastic wrap. Chill dough on a baking sheet until firm, at least 4 hours. (To roll cookies into balls, see cooks’ note, below.)
- Put oven racks in upper and lower thirds of oven and preheat oven to 375°F.
- Cut enough 1/8- to 1/4-inch-thick slices from log with a heavy knife to fill 2 ungreased large baking sheets, arranging slices about 1 inch apart (chill remainder of log, wrapped in plastic wrap). If garnishing with coarse sugar, sprinkle slices with it.
- Bake cookies, switching position of sheets halfway through baking, until edges are golden, 12 to 15 minutes total. Cool on sheets 3 minutes, then transfer with a metal spatula to racks to cool completely. Make more cookies with remaining dough on cooled baking sheets.