Preheat oven to 375°F. Line a baking sheet with muffin liners, or grease and flour the tin. Set aside.
In a medium bowl, combine flour, chocolate chips, baking soda, and salt.
In a separate bowl, mash bananas until smooth. Add egg, butter, vanilla, and combine. Pour flour mixture into banana mixture, and mix until combined, ensuring you don't over mix the batter.
Add batter in equal portions to the prepared muffin tin, using a cookie scoop works best.
Bake for 20 minutes, or until a toothpick inserted into the center of the muffins comes out clean.
Cool on a cooling rack before serving.
Notes
Avoid over mixing the batter, it will result in dense muffins.