Preheat oven to 350 degrees F. Line two cookie sheets with Reynolds® Parchment Paper; set aside.
Beat the butter and sugar in a large bowl using an electric mixer about 2 minutes or until light and fluffy. Add the egg, orange peel, lemon peel, and vanilla and beat until well blended.
Combine the flour, baking powder, and salt in a medium bowl. Add half of flour mixture to the butter mixture, beating until just combined. Add the milk. Beat about 10 seconds. Beat in the remaining flour mixture until just combined.
Drop tablespoon-size mounds of dough on prepared cookie sheets.
Bake 8 to 10 minutes or until set and the bottoms are browned. Transfer the cookies on the parchment paper to a wire rack; cool completely.
Drizzle with Citrus Glaze to serve.
Citrus Glaze: In a small bowl combine melted butter and orange juice. Add powdered sugar; beat until smooth. If necessary, add more orange juice, 1/2 teaspoon at a time, to make drizzling consistency. Drizzle over cookies.