Place the freezing moulds on a tray. Fill 1/3 of the moulds with cherry nectar, close them and place them carefully in the freezer. Let the nectar freeze. Peel banana, cut a little smaller. Add yoghurt and vanilla sugar and puree with a hand blender.
Fill into the moulds. Close the moulds again and let them freeze for about 1 hour. Rinse ice moulds with cold water to make them easier to remove from the mould. Place on small plates and decorate with lemon balm