Royal Icing

from Alton Brown: 

Ingredients 

3 ounces pasteurized egg whites 

1 teaspoon vanilla extract 

4 cups confectioners' sugar 

 Directions 

 In large bowl of stand mixer combine the egg whites and vanilla and beat until frothy. Add confectioners' sugar gradually and mix on low speed until sugar is incorporated and mixture is shiny. Turn speed up to high and beat until mixture forms stiff, glossy peaks. This should take approximately 5 to 7 minutes. Add food coloring, if desired. For immediate use, transfer icing to pastry bag or heavy duty storage bag and pipe as desired. If using storage bag, clip corner. Store in airtight container in refrigerator for up to 3 days. ****Consumption of raw or undercooked eggs, shellfish and meat may increase the risk of foodborne illness.

From NY TIMES Cooking:

• 3 ¾ cups/1 pound/454 grams confectioners’ sugar
• 3 large egg whites
• ½ teaspoon cream of tartar
•  Pinch kosher salt
•  Food coloring, as needed