I've just doen a search on this as I couldn't think that it wouldn't have been suggested before but it isn't coming up ....
Just peel a banana, wrap it in tinfoil and freeze it!
No need to defrost, they're edible straight from the freezer(ie. not ROCK hard) and have the consistency of ice-cream.
You CAN roll it in a bit of splenda for a sweet crunchy coating but they're fine without. It's more like having a desert or an ice-cream than just another plain old piece of fruit!