2. Puree the bananas, vanilla or rum and lemon juice in a food processor. Add the sugar to taste. (This will depend on how ripe the bananas are.)
3. In a large bowl, mix the banana mixture with about 1/2 cup of the frozen yogurt or ice cream until it is thoroughly combined. Fold in the rest of the frozen yogurt or ice cream quickly. Spread this on top of the cookie crumbs in the pie pan and freeze for at least 2 hours.
4. When ready to serve, remove the pie from the freezer and set aside. (The pie needs to soften a bit before slicing it. If the pie has been in the freezer overnight, leave it at room temperature for about 5 minutes before serving.)
5. Whip the cream and confectioners' sugar to soft peaks. Decorate the top of the pie with the whipped cream, topped with the remaining cookie crumbs. Cut into wedges and serve.