Measure out the white sugar and add it to the mixing bowl.
This recipe doesn’t use powdered sugar like most other buttercream recipes as we’ll be dissolving it in the egg whites.
Place the mixing bowl with the egg whites and sugar over a saucepan on medium high heat with a few inches of boiling water. Using a whisk mix the ingredients together to dissolve the sugar.
Using a clean hand, feel a small amount of the mixture between your fingers, if it’s smooth the sugar has been dissolved and it can be removed from the heat.