Angel food cake is usually baked in a tube pan, a tall, round pan with a tube up the centre that leaves a hole in the middle of the cake. A bundt pan may also be used, but the fluted sides can make releasing the cake more difficult. The center tube allows the cake batter to rise higher by 'clinging' to all sides of the pan. The angel food cake pan should not be greased, unlike pans used to prepare other cakes. This allows the cake to have a surface upon which to crawl up, helping it to rise. After baking, the cake pan is inverted while cooling to prevent the cake from falling in on itself. Angel food cake is sometimes frosted but more often has some sort of sauce, such as a sweet fruit sauce, drizzled over it. A simple glaze is also popular. Recently, many chefs (Alton Brown in particular) have popularized the idea of adding aromatic spices such as mace and cloves to the cake.