Preheat oven to 350 degrees.
Mash three ripe bananas with a fork. Set aside.
In a medium bowl, mix flour, baking powder, baking soda, salt, cinnamon, and brown sugar.
In a large bowl, combine egg, applesauce, vanilla, and bananas.
Pour dry ingredients into the large bowl of wet ingredients and add chocolate chips.
Stir until all the flour has been incorporated. Don't over stir.
Prepare a muffin pan with cooking spray and divide the batter between the 12 muffins cups in the pan.
Bake in 350 degree oven for 20-25 minutes or until a toothpick inserted in the center comes out clean.