This sugary icing makes a great topping for cookies, but it can also be used to decorate cupcakes and cakes. It dries to a hard, white, shiny gloss; food coloring can also be added. Cookie Recipes
In a medium bowl, beat the egg white at medium speed until foamy. Add the confectioners' sugar, 1 cup at a time, beating between additions, until the sugar is completely incorporated. Add the water and beat at high speed until the icing holds its shape, about 5 minutes.
Spoon the icing into a piping bag fitted with a plain tip and use at once; thin with water if necessary.