Make sure your utensils and bowl are completely clean, dry, and free from grease before you begin. Otherwise the icing won’t peak properly. Make sure, if you have separated the eggs, that there is no yolk mixed in.
In the bowl of a stand mixer, combine all of the ingredients and mix on the lowest speed until the sugar combines with the egg whites. Turn mixer up to medium-high and mix for 6 minutes. Do not over-beat the icing or it will become stiff, dry and difficult to use!
Remove icing from the mixer and store in the refrigerator, covered with a tight lid or plastic wrap applied directly on top of the icing, for up to a week.