Peel and thinly slice bananas, place them on a single layer on a freezer safe tray, and freeze.
When bananas are frozen, put all ingredients into a high speed blender or food processor, and blend until smooth and creamy. You may need to start just by pulsing, and scraping down the sides of the blender if necessary.
Pour into a freezer proof dish, cover and freeze for at least two hours. Depending on your freezer, you may need to leave it at room temperature for 20 minutes before serving. The consistency should be like that of soft serve, or frozen yoghurt.
Serve in bowls or glasses, topped with more Tatua Creme Fraiche and fresh berries.