Snow, also known as snow cream, is a dessert of old lineage, possibly brought to England during the reign of the Plantagenets, that became popular in the 16th century. Variations of it are still popular today. Snow can be eaten hot or cold. The basic recipe is egg whites, cream, rosewater or another flavoring agent, and sugar, whipped until stiff. It was traditionally presented at festive occasions draping another item to give the appearance of snow. For a more luxurious effect, gold leaf would be added. Apple snow, with puréed apple added to the basic recipe, was popular served hot in the 17th century while a more modern version is eaten cold. There is a Russian version that is called air pie, which is egg white, sugar, and fruit pureé, whipped and served hot. Snow cake is simply a cake with egg whites as its base: it is not related to snow cream desserts.
References
Davidson, Alan. Oxford Companion to Food (1999). "Snow", p. 731
