Place frozen bananas in chunks into the Thermomix bowl and blend 10 sec/speed 8.
Add Notella and blend 15 sec/speed 8. Insert Butterfly. Whip 20 sec/speed 4 or until fluffy and aerated.
Serve immediately or store in an ice cream storer. It will quite hard after 24 hours in the freezer, but just take it out of the freezer and put it in the fridge for about 15 minutes prior to serving.