3 tablespoons hot water
1 cup confectioner's sugar (powdered sugar)
1 unbeaten egg white
1/4 teaspoon cream of tartar
1/2 teaspoon salt
1 teaspoon vanilla
Stir and boil water and sugar in a pan until sugar completely dissolves.
Put egg white, cream of tartar and salt in a mixing bowl. Add hot sugar syrup. Beat at high speed (adding vanilla as you beat) until it's spreading consistency - about 3 minutes. Let cool a bit before icing the cake.