Preheat oven to 350 degrees (180 degrees C).
Spray an 8 1/2 x 4 1/2-inch bread load with Nonstick Cooking Spray (to taste). Combine Whole Wheat Flour (1 2/3 cup), Baking Powder (2 teaspoon) and Salt (1 teaspoon) in a medium bowl. Set aside.
In this order, add ingredients to the Vitamix: Egg (1), Granulated Sugar (2/3 cup), Unsalted Butter (1/4 cup) Non-Fat Milk (1/3 cup), 1 tsp zest of the Lemon (1), Banana (2), and Apple Sauce (1/4 cup). Variable 1-5, 15 seconds or until mixed.
Pour the wet ingredients into the mixing bowl with dry ingredients and mix gently by hand or with a spatula to combine. Fold Walnut (2/3 cup) in after the dry and wet ingredients are mixed, reserving some walnuts for topping later.
Bake for an hour, check if fully cooked with a toothpick. It is cooked when an inserted toothpick comes out clean. Let it cool and serve.