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).
Remove the frozen bananas from the freezer and put them in a food processor. Add the rest of the ingredients but the nuts and pulse.
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 nuts: put them on a baking tray in a 300°F preheated oven for 5 minutes or put them in a skillet over low heat for 3-5 minutes. Let them cool completely before you sprinkle them over the ice cream.