Mash the sugar and bananas together in a large bowl.
Add the melted margarine and stir in. Add the flour and baking powder and mix well. Then stir in chocolate chips. Place mixture in a greased or lined loaf tin, cake tin or muffin tin.
Bake in preheated oven for about 20 to 30 minutes, depending on which tin you are using. Muffins cook a little quicker. Check by sticking a clean knife or skewer into the cake and it should come out clean when done.
Icing: Mix together icing sugar, buttery spread and cocoa powder in a food processor or with a wooden spoon. Spread over cooled cake.
Previously frozen bananas work well for this recipe, so if you have any bananas which go too ripe and are not going to be eaten, freeze them to keep for this recipe.