MICROWAVE chocolate and butter in small microwaveable bowl on HIGH 1 min. or until butter is melted; stir until chocolate is completely melted and mixture is well blended. Spread onto bottom of crust. Refrigerate 10 min.
BEAT pudding mixes and milk in medium bowl with whisk 2 min. (Pudding will be thick.) Stir in half the COOL WHIP; spoon into crust.
REFRIGERATE 3 hours or until firm. Garnish with remaining COOL WHIP before serving.