Mix all the dry ingredients; flour, cocoa, baking powder and sugar in one bowl

In a separate bowl, mash the banana using a fork, add the eggs and mix then add your melted margarine and mix.

Add the dry ingredients in the bowl containing the wet ingredients and mix until you achieve a thick paste

Prepare your baking tin by oiling it then dusting with flour or lining it with a parchment paper

Pour the butter into the baking tin and bake in a 180 degree preheated oven for 30minutes depending on the accuracy of your oven.