01 - Preheat oven to 350°F. Line a 12-cup muffin tin with paper liners or lightly grease each cup.
02 - In a large bowl, whisk mashed bananas, eggs, vegetable oil, granulated sugar, brown sugar, and vanilla extract until smooth.
03 - Sift together flour, cocoa powder, baking soda, baking powder, and salt in a separate bowl.
04 - Add dry mixture to the wet ingredients. Stir gently with a spatula until just combined; avoid overmixing.
05 - Fold in most chocolate chips, reserving a few for topping.
06 - Divide batter evenly among muffin cups, filling each about three-quarters full. Sprinkle reserved chocolate chips on top.
07 - Bake for 18 to 22 minutes or until a toothpick inserted in the center comes out with a few moist crumbs.
08 - Allow muffins to cool in the tin for 5 minutes, then transfer to a wire rack to cool completely.