Preheat your oven to gas mark 4.
In a large bowl, whisk the egg, sugar and melted butter until you have a plain mix that has increased in volume.
Take half a banana and place to one side for later.
Roughly mash the rest of the bananas until you have a combination of pureed and lumpy banana then add to the other wet ingredients.
Add the chocolate chips before folding in the flour.
Line a loaf tin with greaseproof paper and pour in the mix.
Slice the half a banana placed to one side earlier and add to the top of the mix for decoration.
Place in the centre of the oven and cook for an hour (or until the top of the cake bounces back when prodded gently with the tip of your finger).
Let the cake cook in the tin for ten minutes before turning out on a cooling rack.
This banana bread is best served warm and can be reheated.