Carefully peel the banana and use a sharp knife to cut it in half lengthwise, being careful not to break the halves.

Place peanut butter in a small glass dish and microwave about ten seconds to soften. Delicately spread the peanut butter on one half of the cut banana. Close the sandwich with the other banana half. Wrap it in wax paper and freeze for two hours. Enjoy it frozen or slightly thawed.