1. Preheat your oven to 375 F (190 C). Line a 12-cup muffin tin with paper liners or lightly grease each cup.

2. In a large mixing bowl, whisk together the whole wheat flour, all-purpose flour, rolled oats, baking soda, baking powder, ground cinnamon, and salt.

3. In a separate medium bowl, mash the ripe banana thoroughly. Then, add the unsweetened applesauce, maple syrup (or honey), milk, egg, and vanilla extract. Whisk these wet ingredients together until they are well combined and smooth.

4. Pour the wet ingredient mixture into the bowl with the dry ingredients. Stir gently with a spatula or wooden spoon until just combined. Do not overmix.

5. Gently fold in the shredded carrots, chopped walnuts (if using), and raisins or dried cranberries (if using).

6. Divide the batter evenly among the 12 prepared muffin cups, filling each cup about two-thirds full.

7. Bake for 20-25 minutes, or until a wooden skewer or toothpick inserted into the center of a muffin comes out clean. The tops should be golden brown and spring back lightly when touched.

8. Remove the muffin tin from the oven and let the muffins cool in the tin for a few minutes before transferring them to a wire rack to cool completely.