Preheat oven to 350 degrees F. Lightly coat a 9x5 inch pan with nonstick cooking spray. In a large bowl, combine first six ingredients; set aside. In another large bowl, beat egg whites until foamy. Add bananas, buttermilk, applesauce and vanilla. Stir into dry ingredients until just blended. Add nuts. Pour into prepared pan and bake 45 to 55 minutes or until golden.
Serves 12, 215 Calories per serving.
Note: If you leave out the walnuts you can reduce the calories per serving to 183.