Peel and slice the bananas and put them in a freezing bag or container. Put in the freezer overnight or until they are frozen (minimum 4 hours).
There are two ways to make the ice cream
1) with the nuts mixed in with ice cream.
2) or to crush them and sprinkle them over.
To make the ice cream
remove the frozen bananas from the freezer and put them in a food processor. Add the rest of the ingredients and pulse. Every now and then scrape down the sides with a spatula. Pulse until the mixture has the texture of a soft-serve ice cream. Put the ice cream in a container and freeze up to two weeks.
To toast the hazelnuts, simply put them on a baking tray in a 300°F preheated oven for 5 minutes or put them in a skillet over low heat. Let them cool then peel them by rubbing handfuls of them with your hands.