If possible, take out the bananas and the frozen milk out of the freezer 5 to 10 minutes before preparing your nice cream. Mix all the ingredients in a blender. Adjust the thickness according to your preference: add some more rice milk or water to obtain a smoothie or put it in the freezer for another 30 minutes for an even harder consistency.
Sprinkle with berries or granola.
Notes
It's not necessary to to freeze the milk before, but this will help to obtain a thicker smoothie or nice cream. I always keep in the freezer some frozen milk, that i put in an ice cube tray or in a tupperware.