Preheat your oven to 350 degrees F (176 C).
In a mixing bowl, combine the butter and sugar until creamy. Add the rest of the wet ingredients; mashed bananas, applesauce, egg whites and vanilla and stir. Set aside.
In a medium bowl combine the dry ingredients; flour, baking soda, baking powder, xanthum gum and salt. Mix together.
Slowly, a little a time use a fork to mix the dry ingredients into the wet ingredients.
Use a little spay oil to coat the bottom and sides of a loaf pan and then flour your pan. Alternatively you can line your pan with parchment paper. This is to prevent sticking.
Heat up your nutella for about 30 seconds in the microwave to soften slightly.
Spoon half of the batter into the prepared loaf pan. Drizzle half of the nutella on top of batter. Repeat with the second half of the batter and then follow with a final drizzle swirl back and forth on top.
To make a fun design on top of your nutella bread run your knife shallowly in the opposite direction of the swirls.
Bake your almost diet nutella banana bread for about 45 minutes or until the toothpick comes out clean. Allow to cool.
Run your knife gently around the edges of the bread within the loaf pan. Slice and serve plain or with a little butter, hugs, kisses and some homemade cards for mom.