1 1/2 c. dark brown sugar, packed
2 egg whites, at room temperature
1/3 c. water
1 tsp. vanilla

Combine brown sugar, egg whites, and water in top of double boiler; place over boiling water. Stir until sugar dissolves. Beat with mixer 7 minutes until frosting holds soft peaks. Remove from heat, beat in vanilla. Frosts a 9-inch layer cake.