Before you even bake it, make sure to grease the pan with butter and flour — or in this case, cocoa powder. Once it's out of the oven, place the pan on a wire rack and let it cool for about 10 minutes. Then, flip the cake onto the rack to finish cooling. If you try to flip it too early, the hot cake will collapse or break apart. But if you wait too long, it might get stuck in the pan.