3 large bananas, very ripe, peeled and frozen in advance
Make the Nice-cream one day before you plan to serve it.
Combine the ingredients in a food processor and whizz until smooth. Spoon into a zip lock bag and lay flat and squeeze as much air out as possible. Freeze overnight. The next day remove from the freezer bag, and whizz in the food processor until all the chunks are broken up (it will look like soft serve).
Place in a freezer container and freeze again until serving.