Preheat oven to 350°F (175°C). Grease and flour a 9×5 inch loaf pan.
In a large bowl, mash the bananas. Add the applesauce, maple syrup, coconut oil, eggs, greek yogurt (or cottage cheese), and vanilla extract. Mix until well combined.
Stir in the protein powder until smooth.
In a separate bowl, whisk together the oat flour, baking soda, cinnamon, and salt.
Gradually add the dry ingredients to the wet ingredients, mixing until just combined. Be careful not to overmix!
If using, gently fold in the chopped nuts and/or peanut butter.
Pour the batter into the prepared loaf pan. Bake for 45-55 minutes, or until a wooden skewer inserted into the center comes out clean.
Let the bread cool in the pan for 10 minutes before transferring it to a wire rack to cool completely.
