Ingredient substitutions usually are a last resort and a lesser alternative to a missing ingredient, but in some cases the substitute can be an improvement. For example, replacing water with coffee in chocolate cake recipes can deepen and enhance the chocolate's flavor.
Brew coffee to the desired strength using a coffee maker or the stovetop. Allow the coffee to cool, unless the recipe states otherwise.
Prepare the recipe as written. When it's time to add the water, measure out the required amount of coffee (for example, replace 1 cup of water with 1 cup of coffee). Mix it in according to the recipe's directions.
Bake as directed. When checking for browning, remember that the coffee might darken what would normally be a lighter-colored cake.