Royal icing is very versatile. It is pure white and dries very hard, so it is perfect for making flowers and bows and delicate piped work. It can be kept in an airtight container at room temperature for 2 weeks. You should stir the icing to restore its original consistency after storage, but do not rebeat. Royal icing does not work well in high humidity.
Place all of the ingredients in the bowl of an electric mixer and beat slowly until they are all blended. Then beat at medium speed until the icing forms stiff peaks, about 5 minutes. Add more sugar if the icing is not stiff enough, or a few drops of water if it is too stiff. Use immediately or cover the bowl with a damp cloth to prevent drying when not in use. Allow at least 24 hours for royal icing decorations to dry, at room temperature.
Consumption of raw or undercooked eggs, shellfish and meat may increase the risk of foodborne illness.
Recipe courtesy of Colette Peters, Colette's Christmas, Little, Brown & Co., 1993