Royal Icing

3/4 cup warm water
5 Tablespoons Meringue Powder
1 teaspoon Cream of Tatar
9 cups Powdered Sugar
1 teaspoon Clear Vanilla
food coloring

In mixer bowl, pour in the warm water and the meringue powder. Mix it with a whisk by hand until it is frothy and thickened...about 30 seconds.
Add the cream of tartar and mix for 30 seconds more.
Pour in all the powdered sugar at once and place the bowl on the mixer.
Using the paddle attachment on the LOWEST spped, mix slowly for a full 10 minutes. Icing will get thinck and creamy.
Cover the bowl with a dampened tea-towel to prevent crusting and drying.
Tint with food colorings. Thin the icing with small amounts of warm water to reach the desired consistency.
Frosts about 10 dozen cookies. You can store the icing in plastic tubs for up to two weeks.

For tips and other directions on how to use the frosting, check out Sweetopia. That is where I learned all I know about frosting cookies with Royal Icing.