Preheat the oven to 350°F (175°C) and line a 12-cup muffin tin with paper liners or grease with cooking spray.
In a large mixing bowl, mash the ripe bananas with a fork until smooth.
Add the eggs, unsweetened applesauce, honey, and vanilla extract to the mashed bananas and whisk until well combined.
In a separate bowl, whisk together the whole wheat flour, vanilla protein powder, baking soda, baking powder, ground cinnamon, and salt.
Gradually add the dry ingredients to the wet ingredients, stirring gently until just combined. Do not overmix.
Fold in the chopped walnuts evenly throughout the batter.
Divide the batter evenly among the 12 muffin cups, filling each about 3/4 full.
Bake in the preheated oven for 18 to 20 minutes, or until a toothpick inserted into the center of a muffin comes out clean.
Remove the muffins from the oven and allow them to cool in the tin for 5 minutes.
Transfer the muffins to a wire rack to cool completely before serving.