An upside-down cake is a single-layered cake that is served upside down. It is prepared by coating the bottom of a cake pan with a mixture of butter and brown sugar and then arranging pieces of fruit in a decorative pattern. Cake batter is poured over the fruit. After baking, the cake is inverted onto a serving plate so that the fruit and caramelized sugar mixture provide a topping for the cake. Pineapple and peach upside-down cakes are the most common types.