Preparation Blend together butter, sugar, and zest with a rubber spatula. Add egg white and stir until combined well. Sift together flour, cinnamon, baking powder, and salt onto butter mixture and stir until flour is just incorporated. Chill dough, covered (or in pastry bag if using), until firm but not hard, about 1 hour. Preheat oven to 325°F. Pipe or drop 1/2-teaspoon mounds about 3 inches apart onto lightly buttered baking sheets and bake in batches until edges are golden, 10 to 12 minutes. Cool cookies on sheets until warm (about 2 minutes), then transfer to a rack to cool completely. Cooks' note:Cookies keep in an airtight container at room temperature 1 week.
Preparation Blend together butter, sugar, and zest with a rubber spatula. Add egg white and stir until combined well. Sift together flour, cinnamon, baking powder, and salt onto butter mixture and stir until flour is just incorporated. Chill dough, covered (or in pastry bag if using), until firm but not hard, about 1 hour. Preheat oven to 325°F. Pipe or drop 1/2-teaspoon mounds about 3 inches apart onto lightly buttered baking sheets and bake in batches until edges are golden, 10 to 12 minutes. Cool cookies on sheets until warm (about 2 minutes), then transfer to a rack to cool completely. Cooks' note:Cookies keep in an airtight container at room temperature 1 week.