7 MINUTE FROSTING
In the heatproof bowl set over a saucepan of simmering water, combine sugar, corn syrup, 1/4 cup water, and egg whites. Cook over medium heat, stirring frequently, until mixture registers 160 degrees on an instant-read thermometer, about 2 minutes. Remove from heat using hand mixer beat mixture on high using whisk attachment if you have one until glossy and voluminous, about 5 minutes. Beat in vanilla. Use immediately.