Grease a 12-cup or 24 mini-cup muffin tin with oil spray.
Mix the All Bran Cereal and the skim milk in a small bowl and let stand while you prepare the other ingredients.
In a large bowl mix the oat bran, flour, sugar, baking powder, baking soda, salt, and cinnamon.
In a small bowl, combine the banana, egg, vegetable oil, and applesauce. Stir in the All Bran mixture and blueberries. Stir this mixture into the dry ingredients, and mix ONLY until incorporated. DO not over mix.
Spoon mixture into prepared muffin tin. Bake for 20 minutes for the larger muffins or 15-18 minutes for the mini muffins. Bake until golden on top.
Cool for 5 minutes in the tin. Remove the muffins and let cool on a wire rack.