There's barely a recipe, really... I just slice about half a dozen bananas, freeze them, then put them in a food processor with about 150g of whey protein and add as much milk as it takes to get a soft serve consistency. Then I put it back in the freezer and take a few scoops when I'm craving something sweet.

It's fully customizable, you can use food flavoring instead of the whey, maybe add honey or peanut butter, blend some other frozen fruit along with the banana, you name it.