Place ripe bananas, 1 per serving, directly into the freezer unpeeled. The peel will serve as a protection in the freezer. Freeze solid.
Just before serving, peel off the skin with a small paring knife ( a little trickier than it sounds), cut the banana into chunks & place in a blender or in a food processor fitted with a steel blade. Blend until the banana breaks up, passes the icy stage & becomes creamy & whipped with air. The consistency should be that of frozen custard.