Preheat your oven to 350°F (175°C). Line a loaf pan with parchment paper or grease it well with oil or cooking spray.
In a large bowl, mash the ripe bananas with a fork. Add the eggs, Greek yogurt, maple syrup (if using), and vanilla extract. Whisk until smooth and combined.
In a separate bowl, mix oat flour, protein powder, baking soda, baking powder, cinnamon, and salt. Gradually stir the dry mixture into the wet ingredients until just combined.
If using, gently fold in any optional add-ins like nuts, chocolate chips, or seeds.
Pour the batter into the prepared loaf pan and smooth the top. Bake for 40–50 minutes, or until a toothpick inserted into the center comes out clean.
Allow the bread to cool in the pan for 10 minutes, then transfer to a wire rack to cool completely. Slice and serve.