Finally, most bakers dread the random air bubble that wreaks havoc on a sliced cake's appearance. But this type of aesthetic imperfection can be avoided by dropping the pan on a countertop to burst any air bubbles. Once you pour your batter into the pan, smooth its top with a rubber spatula. Next, drop the pan from the height of about a foot onto countertop. The impact of the fall will force large air bubbles out and settle the batter into the pan, producing a more even shape. Only do this for cakes leavened with baking soda or baking powder, however; egg foam cakes, like genoise, need their air bubbles in order to rise.