Frozen ( or not ) Grasshopper Pie

Back in the olden days -- the 70's --- Grasshoppers were a popular  frozen minty  cocktail  made with green crème de menthe and vanilla ice cream.   Soon a recipe circulated among our card club for  frozen  grasshopper pie one of the hostesses served.   I haven't made this for....um.... let's say 40 years,  until it popped up in  a magazine recently... Food Network,  maybe.  They don't mention freezing it, but that's the way we enjoyed  it.    Just let it set out for 10 or 15 minutes to thaw a bit  before cutting.   Here goes:

Melt 24  regular-size marshmallows in 2/3 cup half -and-half cream in a double boiler  or very slowly & carefully over low heat.  Remove the pan and let it cool before folding in 2 TB white crème de cacao and 2 TB green crème de  menthe.  Fold in 1/2 pint whipping cream, whipped, and pour the filling into a  9" chocolate crumb crust.  Freeze for at least 3 hours or chill  for at least 1 hour.    Serve topped  with more whipped cream,  a few crushed chocolate cookies, and   fresh mint leaves.  I think  we sometimes dribbled a  few  tablespoons  of crème de menthe over the  whipped cream when we served it.