In a bowl, sift flour, baking powder, baking soda, and salt.
In a separate bowl, mix together bananas, sugar, egg, and melted butter
Fold in flour mixture, and stir until smooth. Scoop batter into greased muffin cups. Sprinkle with cinnamon and sugar.
Bake for 25 to 30 minutes.
Bake mini muffins for 10 to 15 minutes.