Preheat oven to 400°F (200°C).

Spray muffin cups with cooking spray.

In a medium bowl, combine oat bran cereal, mashed bananas, egg whites, skim milk, and corn oil.

Let the mixture stand for 5 minutes.

In a large bowl, combine flour, brown sugar, and baking powder.

Add the cereal mixture to the flour mixture, stirring just until moistened.

Spoon the batter into the prepared muffin cups.

Sprinkle chopped walnuts on top of each muffin.

Bake in the preheated oven for about 20 minutes, or until lightly browned and firm to the touch.

Serve warm with Mazola margarine.