There are numerous online sources that have simple royal icing recipes, such as Food Network, Southern Living and Wilton. At the Food Network site, Alton Brown provides a simple recipe that consists of three ingredients, which are confectioner sugar, pasteurized egg whites and vanilla extract. These ingredient are combined in a bowl and then mixed for about 6 minutes until the mixture forms stiff peaks.
Southern Living and the Wilton websites also have basic recipes that take a few minutes to make. However, the recipes on both these sites use meringue powder instead of egg whites. A coloring agent can be added to royal icing. Royal icing is often used to decorate sugar cookies and other baked goods.