In a small bowl, combine coconut and butter. Press onto the bottom and up the sides of a greased 9-in. pie plate. Refrigerate for at least 30 minutes or until firm., In a small bowl, whisk milk and pudding mixes for 2 minutes. Let stand for 2 minutes or until soft-set. Spread 1-1/2 cups over crust. , Fold whipped topping into remaining pudding; spread over pie. If desired, sprinkle with chopped pistachios. Cover and refrigerate at least 2 hours before serving.