Makes: about 3 1/2 dozen cookies
Mix flour, baking powder and salt in a bowl; set aside. Beat butter, sugar, egg and vanilla in clean bowl until blended. Stir in flour mixture. Gather into ball. Wrap and refrigerate several hours or overnight.
Drop by rounded teaspoonsfuls, 2 inches apart, onto prepared baking sheets. Bake 10 to 12 minutes, until lightly browned around edges.
Prepare Vanilla Glaze. Tint one quarter of glaze with red food coloring, one quarter with green. Spread cookies with white glaze. Drizzle with colored glaze.