Preheat oven to 350 degrees Fahrenheit (175 degrees Celsius) and grease a 12-cup muffin tin or line with paper liners.

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

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

Gradually fold the dry ingredients into the wet mixture until no dry streaks remain, being careful not to overwork the batter.

Distribute the batter evenly among the 12 muffin cups, filling each approximately three-quarters full.

Bake for 18 to 22 minutes or until the tops are golden brown and a toothpick inserted into the center comes out clean.

Remove from the oven and allow to cool in the pan for 5 minutes before transferring to a wire cooling rack.