Raise heat and bring to a boil, washing down the sides of pan with a wet pastry brush to prevent crystals from forming. Continue boiling 5-7 minutes until a candy thermometer registers 230*.
Meanwhile, in a mixing bowl, whisk egg whites on medium speed until soft peaks form, about 2 1/2 minutes. Gradually beat in remaining 1/4 cup sugar. Reduce speed to medium-low.
When syrup reaches 230*, carefully pour it in a stream down the side of the bowl while beating egg mixture. Beat until frosting is cool, thick and glossy- 5-10 minutes. Use immediately.
Time to Prepare: More than 7 minutes! (maybe 20)
Servings: Frosts one layer cake
Submitted By: Betsy
Original Source: Martha Stewart Living
Many 7-minute frosting recipes I've tried turn out grainy if not done exactly right. This one has been perfect for me every time.