Sugar glue is a must have for cake and novelty bakers. Edible glue makes 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 while at the same time tastes great.
Separate the eggs and place the whites in the bowl of a stand mixer or in a large bowl to hand beat. Discard the yolks or reserve them in the fridge for a future recipe (such as a chocolate custard).
Beat the whites in the stand mixer on low or by hand with a whisk, until they are frothy and bubbly, about one to two minutes.
Add 1 1/2 tsp cream of tartar and increase machine or arm speed. Beat until the whites begin to peak, about two more minutes in the mixer, or three to four more minutes with your arm. Do not beat until the peaks are stiff. They should be shiny, soft and gooey.
Add the confectioner's sugar a half cup at a time in between beating, or while the mixer is running at a low speed. 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 your head. If the mixture stays where it is, it is finished.
Use the glue right away or transfer it to a smaller bowl, cover it with plastic cling wrap and keep it in the refrigerator until it is needed. Do not keep it in the refrigerator for more than a day, or the meringue will separate and a layer of water will form.
Make sure you work quickly with the glue once you apply it, as it sets almost instantaneously.