royal icing recipe

Ingredients

1. 2 large egg whites
2. 1/4 teaspoon cream of tartar
3. Pinch of salt
4. 1/2 teaspoon pure vanilla extract
5. 2 3/4 cups confectioners' sugar

1. In a bowl, using a handheld electric mixer, beat the egg whites with the cream of tartar, salt and vanilla at low speed until foamy. Increase the speed to medium and gradually beat in the sugar. Continue beating until the icing is stiff. Use immediately.

http://www.foodandwine.com/recipes/royal-icing