Preheat the oven to 180°C.
Put 12 paper muffin cases into a muffin tin.
Blend or mash the bananas to a pulp.
In a bowl sift together the flour, cocoa, baking powder, bicarbonate of soda and salt.
In a large bowl combine the banana pulp, sugar, egg and melted butter.
Fold in the flour mixture until incorporated.
Then fold in the chocolate chips and distribute evenly.
Spoon equally into the 12 muffin cases.
Bake for 20 minutes or until the muffins spring back to the touch.