01 - Preheat oven to 350°F. Line a 12-cup muffin tin with paper liners or lightly grease.
02 - Whisk together the flour, sugar, baking soda, baking powder, and salt in a large bowl.
03 - In a separate bowl, mix mashed bananas, melted butter, milk, eggs, and vanilla extract until smooth.
04 - Fold the wet ingredients into the dry mixture gently until just combined, avoiding overmixing.
05 - Fold in the semi-sweet chocolate chips evenly.
06 - Divide the batter evenly into muffin cups, filling each about three-quarters full.
07 - Bake for 18 to 20 minutes, testing doneness with a toothpick inserted in the center; it should come out clean or with a few moist crumbs.
08 - Allow muffins to cool in the tin for 5 minutes before transferring to a wire rack to cool completely.