Whether you want to want modify an ingredient of a baking formula to reduce fat or calories or to eliminate an allergen, you must first understand the functions of that ingredient in the formula.
Three ways to modify an ingredient are to eliminate it, reduce it, or substitute another ingredient for it.
Eliminating an ingredient may be the best method if that ingredient does not have a major structural or flavor function in a formula. For example, eliminating the chopped nuts in a brownie or cookie formula does not affect the dough or batter, so this step can be done easily.