01 - Preheat your oven to 350°F. Line a 12-cup muffin tin with paper liners or grease it lightly.
02 - In a large mixing bowl, whisk together the all-purpose flour, cocoa powder, baking soda, baking powder, and salt until well combined.
03 - In a separate bowl, whisk the mashed bananas, granulated sugar, vegetable oil (or melted butter), eggs, vanilla extract, and milk until the mixture is smooth and fully incorporated.
04 - Gently pour the wet ingredient mixture into the dry ingredients. Mix until just combined; be careful not to overmix the batter.
05 - Carefully fold in the semi-sweet chocolate chips into the batter.
06 - Evenly divide the prepared batter among the 12 muffin cups. Sprinkle a few extra chocolate chips on top of each muffin for garnish.
07 - Bake for 18 to 22 minutes, or until a toothpick inserted into the center of a muffin comes out with only a few moist crumbs.
08 - Allow the muffins to cool in the pan for 5 minutes before transferring them to a wire rack to cool completely.