The Kitchn’s Baking School Day 4: All about meringue. Join The Kitchn’s Baking School: Sign up and see all The Kitchn’s Baking School assignments In its most basic, stripped-down definition, meringue is egg whites whipped with sugar. Air is quickly whipped into the egg whites, which makes them billow up to as much as eight times in volume. Pretty neat trick, right? When sugar is added, it not only provides sweetness, but it also helps stabilize the egg whites.