Preheat the oven to 375℉. Lightly spray two mini muffin pans with cooking spray and set aside.
In a medium bowl, mix together the flour, baking powder, baking soda and cinnamon.
In a large bowl, mix together the bananas, sugar, butter, egg and vanilla until smooth.
Slowly mix the dry ingredients into the wet ingredients until just combined.
Divide the batter evenly between the two pans and bake in the preheated oven for 11 minutes, or until a toothpick inserted into the center of a muffin comes out clean.