Preheat oven to 350 degrees F. Spray muffin tin with cooking oil or place liners in muffin tin.
Mash bananas in a medium bowl. Whisk in egg, milk, and sugars. Stir in peanut butter. (Adjust peanut butter amount to your liking) Set aside.
In another bowl whisk together flour, baking soda and salt.
Combine flour mixture with banana mixture until just moistened.
Fold in chocolate chips.
Spoon batter equally into each of the 12 prepared muffin cups.
Bake 20 to 25 minutes or until toothpick inserted into muffins comes out clean.
Cool for 5 minutes the remove to wire rack to finish cooling.