Edible glue makes sugar sculpture, cake decorating and gingerbread houses possible. Egg whites are a natural glue: by themselves they can coat breads and muffins to allow toppings to stick, coat granola to cause clumping, and help pie crusts and puff pastry stick together. Sugar glue made from egg whites is a thick soft “paste” that is best applied with small spatulas or knives, rather than paint brushes. It performs the task of a glue but also tastes good.
Separate pasteurized eggs and place the whites in the bowl of a stand mixer or in a large bowl to hand beat. Keep the egg yolks in the refrigerator for other recipes.
Beat the whites in the stand mixer on low or by hand with a whisk, until they are frothy and bubbly, about 1 to 2 minutes.
Add 1/2 teaspoon of cream of tartar for each egg you used and increase machine or arm speed. Beat until the whites begin to peak, about 2 more minutes in the mixer, or 3 to 4 more minutes with your arm. Do not beat until the peaks are stiff. They should be shiny, soft and gooey.
Add 1 cup of confectioner's sugar for each egg you used, adding it 1/2 cup at a time. Add the sugar while the machine is on low or while you continue to beat by hand. Once all sugar is incorporated, beat until the icing forms stiff peaks. To test if it is finished, remove the bowl from the mixer and hold it upside down over a sink. If the mixture stays where it is, it is ready.
Make sure you work quickly with the glue once you apply it, as it sets almost instantaneously. Use the glue right away or transfer it to a smaller bowl, cover it with plastic film and keep it in the refrigerator until it is needed. Do not keep it in the refrigerator for more than a day, or the egg will separate and a layer of water will form. If you prefer, use pasteurized egg whites from the store rather than separating whole eggs.
Use only pasteurized eggs for this recipe because they are uncooked and carry a risk of foodborne illness.