Preheat the oven to 350˚F. Coat two loaf pans with cooking spray or line 24 muffin cups with paper liners.
In a large mixing bowl, combine the all-purpose and whole wheat flours, baking powder, cinnamon, salt, baking soda, oatmeal, brown sugar, raisins, and walnuts. Stir until well combined.
Place the applesauce, canola oil, eggs, and milk in the bowl of an electric mixer. Blend on high speed until combined, about 1 minute.
Add the applesauce mixture to the flour mixture. Stir until the dry ingredients are just moistened. Do not overmix.
Fill the loaf pans with the batter, dividing it evenly between the 2 pans. Bake for 40 to 45 minutes or until a toothpick inserted in the center comes out clean. Remove from pans and allow to cool on a wire rack before slicing. If you're making muffins, cook for 14-16 minutes or until a toothpick inserted in the center comes out clean.