From The Food Encyclopedia by Jacques Rolland and Carol Sherman
A sweet quick bread made in individual-serving molds in an infinite variety of flavors and styles. Thought to be derived from the French moufflet, meaning soft bread, or the German Muffe, meaning a type of cake, the American muffin differs from the English muffin, which is yeast-risen and cooked on a griddle, because it's chemically leavened with either baking soda or baking powder.
