I'm sorry if this is already down on this thread. I've searched, but can't find it. However, I am new so please make allowances.
Peel and finely chop a banana(s).
Blitz in processor, adding a bit of skimmed/semi skimmed milk until the consistency of soft ice cream.
Try and freeze the chopped bananas spread out on a plate or something because I found out the hard way, that if you blitz in big lumps, it burns out the processor motor