Lightly brush crumbs from cookies with a pastry brush. If necessary, thin the Royal Frosting with a few drops water and tint desired color. Spread 1/2 teaspoon frosting over each cookie. Place on a wire rack over waxed paper. Allow to stand for 4 hours or overnight until dry. Pipe desired letters on cookies. Makes 8 cookies.
Using powdered egg whites, follow package directions for preparing equivalent of 1 egg white. In a bowl beat prepared egg white mixture and cream of tartar until foamy. Gradually beat in confectioners sugar; continue beating until thick and creamy, 2 to 3 minutes. Cover until ready to use.