Put cookies in a plastic bag and crush with a rolling pin. Empty into a bowl and stir in the melted butter. Press the mixture into a 9 inch pie plate to form a shell and freeze for 20 minutes.
Meanwhile, soften the ice cream slightly. Drop in a few gummy worms (that's the Halloween part) and spoon into the pie shell. Top with a thick layer of fudge sauce and freeze for at least 1 hour before serving with optional whipped cream.