A mille-feuille, also known by the names Napoleon, vanilla slice, and custard slice, is a dessert made of puff pastry layered with pastry cream. Its modern form was influenced by improvements made by Marie-Antoine Carême.
Traditionally, a mille-feuille is made up of three layers of puff pastry (pâte feuilletée), alternating with two layers of pastry cream (crème pâtissière). The top pastry layer is finished in various ways: sometimes it is topped with whipped cream, or it may be dusted with icing sugar, cocoa, pastry crumbs, or sliced almonds. It may also be glazed with icing or fondant alone, or in alternating white (icing) and brown (chocolate) or other colored icing stripes, and combed to create a marbled effect.