Preheat oven to 350°F (175°C) and grease a 9x5 inch loaf pan with non-stick spray.

In a large mixing bowl, combine mashed bananas, applesauce, Greek yogurt, eggs, maple syrup, and vanilla extract until smooth.

In a separate medium bowl, whisk together the whole wheat flour, protein powder, baking soda, salt, and cinnamon.

Gently fold the dry ingredients into the wet ingredients using a spatula until just combined, ensuring no large pockets of flour remain.

Pour the batter into the prepared loaf pan and level the surface with a spatula.

Bake for 45 to 55 minutes, or until a toothpick inserted into the center of the loaf comes out clean.

Remove from the oven and allow to cool in the pan for 10 minutes before transferring to a wire rack to cool completely.