Chop the semi-dark and whole milk couvertures separately into small pieces and melt each in a small saucepan in a water bath over low heat to a smooth mass.
Peel the bananas and place on 2 wooden skewers.
Cover half of the banana with semi-dark chocolate and the rest with milk chocolate. Drain a little and place on baking paper.
Melt the white couverture in a water bath, fill it in a freezer bag (cut off a small corner of the bag) and sprinkle the bananas with white couverture. Let the couverture dry.