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 the flour, cocoa powder, baking soda, baking powder, and salt.
03 - In a separate bowl, whisk the mashed bananas, sugar, oil or melted butter, eggs, vanilla, and milk until well combined.
04 - Add the wet ingredients to the dry ingredients and gently mix until just combined; do not overmix.
05 - Fold in the chocolate chips until evenly distributed.
06 - Divide the batter evenly among the muffin cups. Sprinkle a few extra chocolate chips on top of each muffin.
07 - Bake for 18–22 minutes, or until a toothpick inserted into the center comes out with a few moist crumbs.
08 - Cool in the pan for 5 minutes, then transfer to a wire rack to cool completely.