From the Country Kitchen Idea's and Recipe's Web site

Egg Wash Glaze Cookie Icing
	Ingredients and Supplies 1 egg white 1/2 cup powdered sugar food color paint brush
Instructions Bake and cool cookies completely. Whisk the egg white until it is frothy. *Note it is best to use powdered egg whites to eliminate any risk of bacteria. Add the powdered sugar. Paint the cookie with this thin glaze. Allow to dry. Thin small amounts of food color with water. Use a paint brush to paint the cookies.