Directions

1. Preheat the oven to 350, and line a muffin pan with 6 cups. In a large bowl, mash the banana very well with a fork until it's smooth. Next, whisk in the sugar, oil, egg and vanilla extract. Whisk very well until combined.
   
2. In the same bowl, sprinkle the flour, cocoa powder, baking soda, and salt on top. Using a spatula, stir until well-combined. Finally, stir in the chocolate chips, saving a few for the top of the muffins.
   
3. Divide the batter between the muffin cups evenly, and sprinkle chocolate chips on top of each muffin.
   
4. Bake for 18 minutes, or until the muffins are done. They're done when they spring back when pressed gently on the top and a toothpick comes out clean. Remove and cool completely on wire rack.