Preheat your oven to 350°F (175°C) and grease a 9x5-inch loaf pan or line it with parchment paper.

In a large mixing bowl, mash the ripe bananas until smooth.

Whisk in the eggs, Greek yogurt, honey (or maple syrup), and vanilla extract until well combined.

In a separate bowl, mix the oat flour, protein powder, baking soda, baking powder, cinnamon, and salt.

Gradually fold the dry ingredients into the wet ingredients until just combined. Do not overmix.

If using walnuts or dark chocolate chips, gently fold them into the batter.

Pour the batter into the prepared loaf pan and smooth the top with a spatula.

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

Allow the banana bread to cool in the pan for 10 minutes, then transfer it to a wire rack to cool completely before slicing and serving.