This is a method of meringue used to aerate mixes such as sponges and soufflés. It is a raw meringue and as such is usually used in recipes before they are baked. The raw part comes from whisking sugar into raw egg whites, which remain uncooked. The method is an easy one. Just start to whisk your egg whites and once they start to foam add a tablespoon of sugar at a time until it is all incorporated and you have a thick meringue. If the meringue collapses before the end it is probably because the sugar was added too quickly, so be sure to add it gradually.