Combine the ingredients in the metal mixing bowl of your stand mixer and set over a pot filled with boiling water on a range, creating a double boiler.
Whisk by hand for a few minutes until the mixture reaches 110 F on a candy thermometer.
Place the bowl on a stand mixer fitted with the whisk attachment. Whisk on medium speed for 10 minutes.
Increase to high speed and whisk until stiff glossy peaks form, about 5 to 10 minutes more.
Pipe or spread frosting onto desserts.
Using a culinary torch, toast the frosting.
Store in the refrigerator until ready to eat - up to 3 days.
Notes
Make sure the inside of the bowl is totally dry.
Make sure there are no egg yolks mixed in with the egg whites.