If you substitute a different size pan than what your recipe calls for, you will need to adjust your baking time in order for the texture of the bars to not be affected. A trick to get your bar cookies out of the pan easily after baking is to initially line the pan with aluminum foil. The foil should be long enough to hang over both sides of the pan, and will be used as handles for when you lift the bars out of the pan. Visit Baking Equipment section to learn more about the types of baking pans and dishes.