Royal Icing

Step 1

In the bowl of an electric mixer, combine the sugar, egg whites, cream of tartar and salt. Whisk until stiff and glossy.

Step 2

To tint the frosting, divide into small bowls. Cover the ones you aren’t using with plastic wrap; the frosting dries out very quickly. Use a rubber spatula to stir in desired food coloring. Though not necessary, it makes life easier if you make two versions of each color — one that is thick to pipe the outline on the cookie, and one that is thinned out slightly with a little water to flood the outline.

Step 3

Transfer frosting to piping bags fitted with very small round tips (sizes 1 to 2 work best). Pipe frosting onto cooled cookies and let set, at least 2 hours. Or use a pastry of paint brush to decorate cookies with the frosting.