Ingredients
1 cup (2 sticks) unsalted butter, softened
2 cups sugar
2 large eggs plus 1 large egg white
2 teaspoons pure vanilla extract
4 cups sifted all-purpose flour, plus more for work surface
1 teaspoon baking powder
1/2 teaspoon salt
Nonpareils, for decorating
Preparation
Mix butter and sugar on medium-high speed until pale and fluffy. Mix in 2 eggs and vanilla. Reduce speed. Gradually mix in flour, baking powder, and salt. Divide dough in half; wrap in plastic. Refrigerate until firm, at least 1 hour.
Preheat oven to 325 degrees. Roll out dough on a lightly floured surface to 1/4 inch thick. Cut out rounds with a 3 1/2-inch cutter; transfer cookies to parchment-lined baking sheets. Freeze 15 minutes.
Brush egg white over cookies; top with nonpareils. Bake until edges turn golden, 16 to 18 minutes. Let cool on wire racks.
