Preheat oven to 375°F (190°C). Line a regular-sized muffin tin with 12 cupcake liners.
In a medium-sized bowl, whisk together cocoa powder, flour, baking soda, baking powder and salt. Set aside.
In a large mixing bowl, beat margarine, sugar, eggs and vanilla until smooth. Mix in half of the flour mixture, then half of the bananas. Scrape bowl and mix in the remaining flour mixture, followed by the bananas. Fold in the chocolate chips, saving some for the tops if you like.
Spoon batter into the cupcake liners (liners will be pretty full) and press remaining chocolate chips into the tops. Bake muffins for 15-20 minutes, test with a wooden toothpick!
Notes
*In Austria/Europe: use 2 teaspoons Weinsteinbackpulver (cream of tartar baking powder) in place of the baking powder and cream of tartar.Recipe adapted fromOh Sweet Basil.