Seven-Minute Frosting

Makes about 5 1/2 cups
3/4 cup plus 2 tablespoons sugar
1 tablespoon light corn syrup
3 large egg whites, room temperature
Directions
In a small, heavy saucepan, combine 3/4 cup sugar, corn syrup, and 2 tablespoons water. Heat over medium heat, stirring occasionally, until sugar has dissolved. Rub a bit between your fingers to make sure there is no graininess. Raise heat to bring to a boil. Do not stir anymore. Boil, washing down sides of pan with a pastry brush dipped in cold water from time to time to prevent the sugar from crystallizing, until a candy thermometer registers 230 degrees about 5 minutes. (Depending on the humidity, this can take anywhere from 4 to 10 minutes.)
Meanwhile, in the bowl of an electric mixer fitted with the whisk attachment, whisk egg whites on medium speed until soft peaks form, about 2 1/2 minutes. Gradually add remaining 2 tablespoons sugar. Remove the syrup from the heat when the temperature reaches 230 degrees (it will keep rising as pan is removed from heat). Pour the syrup in a steady stream down the side of the bowl (to avoid splattering) containing the egg-white mixture, with the mixer on medium-low speed.
Beat frosting on medium speed until cool, 5 to 10 minutes. The frosting should be thick and shiny. Use immediately.