An upside-down cake is a cake usually made in a pan with a curved bottom. Once cooked, turned over and allowed to set, the cake is eaten upside-down. Usually, chopped fruits such as apples, pineapples and cherries are placed at the bottom of the pan before the batter is poured in, so that they form a decorative topping once the cake is inverted.
Turning the cake upside-down is a critical process; if done improperly, part of it can remain attached to the pan, ruining the final product. To allow for an easier detachment, the bottom of the pan is usually covered with butter or sugar.