Preheat oven to 350 degrees Fahrenheit (175 degrees Celsius) and line a 9x5 inch loaf pan with parchment paper or coat with non-stick spray.

In a large mixing bowl, combine the mashed bananas, Greek yogurt, eggs, maple syrup, and vanilla extract. Whisk until the mixture is uniform.

In a medium bowl, whisk together the oat flour, protein powder, cocoa powder, baking soda, and salt to remove lumps.

Gradually fold the dry ingredients into the wet banana mixture using a spatula until just combined; avoid over-mixing to maintain a soft texture.

Fold in 1/4 cup of the dark chocolate chips.

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

Sprinkle the remaining 1/4 cup of chocolate chips over the surface of the batter.

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

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