Preheat oven to 350 degrees Fahrenheit. Put muffin liner on muffin pan.
In a medium bowl, mix together flour, baking soda, baking powder and salt.
In a stand mixer, cut up the bananas into small pieces. Turn on the mixer to low speed to mash the bananas. Add sugar, egg, melted butter. Take the mixer bowl out of the mixer.
Add the dry ingredients into the banana mixture. With a spatula, gently mix until just incorporated. Using an ice cream scoop, scoop the mixture into the muffin cups.
Bake for 25-30 minutes until the top is light brown.