Preheat the oven to 350 degrees. Spray an 8 inch round or square cake pan with no stick cooking spray.
Place the cocoa, 1/4 cup water, and the banana, into a large blender cup or into the bowl of a food processor that has been fitted with a steel blade. Blend until it is smooth. Add sugar, egg whites, vanilla extract, baking powder, and salt; blend until the mixture is smooth. Add the flour, oat bran, and 1/2 cup water (a little at a time) and blend again until smooth.
Pour the chocolate mixture into the prepared pan. Bake at 350 degrees for 20 to 25 minutes. Wait until the brownies have cooled to cut into servings. Store brownies in the refrigerator. Each brownie: 0 mg cholesterol, 123 calories.
