01 - Preheat oven to 350°F. Line a 12-cup muffin tin with paper liners or lightly grease with butter.
02 - In a large mixing bowl, whisk together mashed bananas, melted butter, sugar, eggs, and vanilla extract until smooth and well incorporated.
03 - In a separate bowl, whisk together all-purpose flour, baking soda, baking powder, and salt.
04 - Gently fold the dry ingredient mixture into the wet ingredients until just combined; do not overmix as this will result in dense muffins.
05 - Fold in the chocolate chips, reserving a small amount for topping if desired.
06 - Divide batter evenly among the muffin cups, filling each approximately 3/4 full. Sprinkle reserved chocolate chips on top of each muffin.
07 - Bake for 18 to 22 minutes, or until a toothpick inserted into the center emerges clean or with a few moist crumbs.
08 - Allow muffins to cool in the pan for 5 minutes, then transfer to a wire rack to cool completely.