Preheat oven to 400 degrees.
Line muffin tins.
In medium bowl combine banana, egg, oil, milk and cereal. Let stand 10 minutes.
Stir to break up cereal.
In large bowl combine flour, sugar, baking powder and soda, salt and nutmeg.
Add cereal mixture all at once to dry mixture. Stir just until moist.
Spoon evenly into muffin cups.
Cook 12 large muffins for 25 to 35 minutes or cook 18 small muffins for 20 to 23 minutes.