Place the oven rack in the middle and preheat the oven to 350° F/175° C.
In bowl of the stand mixer, cream together the butter and sugar until light and fluffy. Mix in the applesauce, cinnamon, and quick oats. Mix in the eggs one at a time, beating well each time, then mix in the grated apple.
In the medium mixing bowl, whisk together the unbleached all-purpose flour, whole wheat flour, and baking soda. Take the mixing bowl off the stand and fold in the flour mixture just until the dry ingredients are incorporated. Add the raisins, folding gently. Pour batter into the prepared pan and sprinkle some cinnamon sugar and more quick oats on top.
Bake in the preheated oven until a toothpick inserted into center of the loaf comes out clean, about 50 to 60 minutes. Allow to cool in the pan about 10 minutes, then cool on a wire rack before serving. Keep leftovers wrapped in plastic wrap for up to 3 days.