Royal icing is a pure white icing that dries to a smooth, hard, matte finish. Besides its smooth, finish it is also easy to color, which makes it a favorite of professionals who use it not only for cookies, but also for intricate piping of decorations like flowers, borders, and lettering. It is simply a mixture of confectioners’ sugar, cream of tartar and egg whites but due to the risk of salmonella when using raw egg whites, most people use meringue powder. Meringue powder is made from dried egg whites and is used to replace fresh eggs.
3 tablespoons meringue powder
1 pound confectioners’ sugar (1 box)
3 tablespoons water
In the bowl of your electric mixer, beat the confectioners' sugar and meringue powder until combined. Add the water and beat at high speed until very glossy and stiff peaks form (5 to 7 minutes). See above information about proper consistency for outlining cookies.
The icing should be stiff enough that a knife drawn though it will leave a distinct separation and not fall back together. If your icing is not that stiff, add confectioners’ sugar by the ½ cupful until you have achieved that consistency.
Before coloring, remove a portion of icing for outlining. To the remaining icing add water, half a teaspoon at a time to the remaining icing until you reach the proper consistency for covering the entire surface of the cookie. To cover or 'flood' the entire surface of the cookie with icing, the proper consistency is when you lift the beater, the ribbon of icing that falls back into the bowl remains on the surface of the icing for a few seconds before disappearing. You will need both consistencies to completely cover the cookies with icing.
Decide what colors you will need for your cookies. Separate royal icing into small bowls and color each as necessary. For best consistency, use paste or gel food colors since liquid food color will make your icing runny. Add colors slowly as they are very concentrated. Stir well to completely incorporate color into the icing. To make black or dark red icing you will need to add more coloring to thoroughly saturate the color. Cover each bowl with a damp paper towel to prevent icing from drying. The icing forms a crust very quickly and any bits of crust that get into the piping bag will clog up the tip—very frustrating!
Prepare as many piping bags as colors you have made. Place a #2 or #3 decorating tip in a 12” piping bag. Fill with 3-4 tablespoons of icing and fold down the top of the bag. Cover the tip as well to prevent icing from drying inside. You can also pipe royal icing using plastic squeeze bottle fitted with a small decorating tip. Piping royal icing from a lightweight baggie is not really ideal.
Place your cookies on a parchment- or foil-covered work surface. Holding the piping bag at a 45 degree angle, outline each cookie with stiff royal icing. When you’ve outlined the whole cookie and reach the beginning of the outline, use a damp toothpick to blend the seam. Allow the outline to dry.
Fill the outline in with the thinned icing, using a small offset spatula, spoon or piping bag. Gently push the icing into all the corners and at the edges. The outline will keep the thin icing in place. If you are using more than one base color, such as for apples with leaves, flood the larger area first and once it’s dry, flood the small area.
For added interest, sprinkle colored sugar crystals on royal icing before it has completely dried. The icing and the sugar will enhance each other. You can also write on dry icing using food coloring markers as we have done here. Allow royal icing to dry completely before storing cookies. Once dry, the cookies can be layered with sheets of parchment or waxed paper and frozen in an airtight container.