How to Make It
In the bowl of a stand mixer fitted with the whisk attachment, beat the egg whites and the salt at medium speed until frothy, about 1 minute. Add the confectioners’ sugar 1 cup at a time until the sugar is incorporated. Add 1 tablespoon of water and beat at high speed for 2 minutes, until the icing holds its shape.
Using a spatula, stir water into the icing 1 teaspoon at a time until you achieve the desired consistency (see Note). Stir in food coloring to dye icing, if desired.
Spoon the icing into a piping bag fitted with a plain tip and use right away.
For cookie decorating, using multiple consistencies of icing will deliver the best results. Outlining icing is firm enough to hold in flooded icing, and give structure to designs. Flooding icing pools and sets to a smooth surface on top of cookies.
Outlining icing: Lift the spatula out of the icing and drizzle a figure “8” on top. You know the icing is the correct consistency when the figure “8” disappears in 8 seconds.
Flooding icing: Lift the spatula out of the icing and drizzle a figure “8” on top. You know the icing is the correct consistency when the figure “8” disappears in 6 seconds.
If you have any concerns about eating uncooked eggs, you can make this icing using pasteurized egg whites or powdered egg whites. You can pasteurize your own egg whites using an immersion circulator. Cook them in a BPA-free resealable baggie set in a 130° water bath for 1 hour.