Peel & slice them - put in freezer until needed.
When you require them slightly defort, add ( either a tablespoon of yoghurt, milk or crem frâiche) blitz & you have a healthy soort of ice cream. I keep ripened bananas in freezer as they're so handy, blitz with cream and they make a sponge filling/ topping etc - add a swirl to yoghurt etc.