1 pound powdered sugar, 3 egg whites (at room temp), 1/2 tsp cream of tartar, 1/2 tsp vanilla. Combine all ingredients in medium size bowl. With mixer, blend until smooth, then beat at high speed until very stiff. Makes 3 cups. (I always end up mixing this icing about 5-7 minutes) NOTE: Because the icing dries very quickly, make each batch just before you are ready to use it. IF you must store for a few hours or overnight, cover tightly with platic wrap. When using, keep container covered with damp cloth or paper towel. Mix in food colors as needed. If icing is too thick when using fine tubes, add a few drops of water. For thicker icing, beat in a little extra powdered sugar.
I make ginger bread houses every year and have been using this recipe. It works great. If you need any baking ideas let me know.