cups all-purpose flour
teaspoon baking powder (omit if making thumbprints, ball cookies, or spritz cookies)
sticks unsalted butter
teaspoon finely grated citrus zest
tablespoon fresh citrus juice
1.Whisk together flour, baking powder, and salt in a large bowl. Beat butter and granulated sugar with a mixer on medium-high speed until pale and fluffy. Beat in egg, citrus zest and juice. Reduce speed to low. Add flour mixture, and beat until combined.