Break them up into pieces.
Place the banana pieces in a container or on a tray (for quicker freeze).
Place bananas in the freezer for at least 6 hours. (do it after lunch if you want ice cream for dessert).
Take bananas out of freezer and place in BlendTec or food processor (add peanut butter if you'd like right now) and cream your nanners.
Place in a bowl and enjoy right away.