Ingredients
4 cups all-purpose flour (spooned and leveled), plus more for working
1 teaspoon baking powder
3/4 teaspoon coarse salt
1 1/4 cups (2 1/2 sticks) cold unsalted butter, cut into 1/2-inch pieces
3/4 cup sugar, plus more for decorating (optional)
1 large egg plus 1 large egg white, lightly beaten
2 teaspoons finely grated lemon zest
Royal Icing for Citrus Sugar Cookies, and desired decorations, such as colored sugars
Preparation
In a food processor, combine flour, baking powder, and salt; pulse to mix. Add butter and pulse until mixture resembles coarse crumbs. Add sugar, eggs, and lemon zest and process until mixture resembles wet sand.
Turn mixture out onto a lightly floured surface; knead several times until dough comes together. Divide into 3 portions; flatten each into a disk. Roll each disk to an 1/8-inch thickness between sheets of parchment. Stack dough (still in parchment) on a baking sheet; refrigerate 20 minutes. (To store, wrap in plastic and freeze on sheet, up to 2 weeks. Thaw until pliable before using.)
Preheat oven to 375 degrees, with racks in middle and lower thirds. Working with 1 dough sheet at a time, peel off parchment (save for baking). With lightly floured cutters, cut dough into desired shapes and arrange, 1 inch apart, on 2 parchment-lined rimmed baking sheets (reroll scraps, if desired). Sprinkle with sugar, if desired. Refrigerate 15 minutes.
Bake until cookies are set but still pale, 7 to 9 minutes, rotating sheets halfway through. Transfer cookies to wire racks and let cool completely. Using a spoon, frost cookies with icing; decorate with sugar, if desired.
