Preheat oven to 400 degrees Fahrenheit.

Spray 12 standard muffin cups with nonstick cooking spray.

In a large bowl, whisk together flour, baking powder, baking soda, and salt until well blended.

In another mixing bowl, whisk together the bananas, brown sugar, oil, egg, and vanilla until well combined.

Using a rubber spatula, add the liquid ingredients into the dry ingredients and blend until just combined.

Using an ice cream scoop, divide batter evenly among muffin cups.

Sprinkle each muffin with some of the cinnamon sugar mixture.

Baking for 20 minutes or until a small, sharp knife comes out clean.

Cool muffins for 5 minutes before removing from pans.