1/4 c. granulated sugar
1 1/4 c. firmly packed light brown sugar
1/2 c. water
1/4 tsp. salt
3 egg whites, stiffly beaten
1 tsp. vanilla

Combine granulated and brown sugar, water and salt in a 1 quart saucepan. Place over heat, stirring constantly, until sugar dissolves. Wipe crystals from side of pan as necessary. Boil, without stirring, until temperature reaches 244-246 degrees on a candy thermometer or until firm ball stage.

Gradually beat hot syrup into beaten egg whites. Add vanilla. Continue beating until frosting reaches desired spreading consistency.