Adding a small amount of cream of tartar when you're beating egg whites—usually 1/8 teaspoon per egg white—speeds up the creation of foam and helps stabilize the structure of those miniscule air bubbles you're whipping up. In baking, this means mile-high meringue pies, melt-in-your-mouth meringue cookies, and angel food cakes that practically float off the plate. (All recipes)