In a large bowl, combine flour, powdered sugar, ground walnuts, cocoa powder and salt; cut in butter until mixture is crumbly. Press mixture onto the bottom and up the sides of a 9-inch pie plate.
Bake in a 350° oven for 8 to 10 minutes or until just set; remove to a wire rack. Increase oven temperature to 375°. In a medium bowl, combine 3/4 cup of the chocolate ice cream topping, the 2 cups cranberries and chopped walnuts; spoon into the hot pie shell. Bake for 18 to 20 minutes or until cranberries just begin to pop open. Cool completely on wire rack.
In a chilled medium mixing bowl, beat whipping cream to soft peaks; set aside. In a large mixing bowl, beat cream cheese until smooth; gradually beat in 1/2 cup chocolate ice cream topping; fold in whipped cream. Spoon over pie. Chill at least 2 hours.
To serve; stir remaining ice cream topping* and drizzle over pie. Add a garnish of cranberries and fresh mint.
If necessary, place the 1/4 cup topping in a small microwave safe bowl and heat on 100% power (high) for 10 seconds.