Preheat oven to 350 degrees. Generously coat a 12-cup muffin pan with cooking spray. I recommend cooking spray with flour in it.
In a blender or food processor, add 2 cups of rolled oats and blend until it becomes an oat flour consistency.
Using an electric mixer, or in a large bowl using a hand mixer, add the oats flour, 1 cup of rolled oats, egg whites, eggs, mashed bananas, applesauce and oil. Mix until combined.
Add brown sugar, whole wheat flour, walnuts, vanilla, baking soda, and salt. Mix until blended. Do not over mix.
Fill batter into coated muffin pan. Fill each muffin cup to the top. Evenly sprinkle remaining ¾ cup rolled oats on top of the muffins.
Bake for about 30 minutes until a toothpick inserted comes out clean.
Remove from oven, cool slightly and remove from pan.