01 - Preheat the oven to 350°F. Line a 12-cup muffin tin with paper liners or grease lightly.
02 - In a large bowl, whisk together flour, cocoa powder, baking soda, baking powder, and salt until evenly mixed.
03 - In a separate bowl, whisk mashed bananas, sugar, oil or melted butter, eggs, vanilla extract, and milk until homogeneous.
04 - Pour the wet mixture into the dry ingredients and gently fold together until just combined; avoid overmixing to maintain tenderness.
05 - Fold in the chocolate chips evenly throughout the batter.
06 - Divide the batter evenly among the muffin cups and sprinkle additional chocolate chips on top of each portion.
07 - Bake for 18 to 22 minutes, or until a toothpick inserted into the center comes out with a few moist crumbs remaining.
08 - Allow muffins to cool in the pan for 5 minutes before transferring to a wire rack to cool completely.