The term 'Muffin Stuff' can be broken down into two crossword solutions: OATBRAN (7 letters) and BRAN (4 letters). Oatbran is a type of cereal made from oat groats that have been ground into a coarse meal. It is high in dietary fiber and is often used as an ingredient in muffins, breads, and other baked goods. BRAN is the outer layer of a grain kernel, which is removed during the milling process. It is also high in dietary fiber and is often used as an ingredient in muffins, breads, and other baked goods. Both oatbran and BRAN are commonly used in muffin recipes to add texture and flavor.