PLACE caramels in medium microwaveable bowl. Add milk. Microwave on HIGH 2-1/2 to 3 min. or until caramels are completely melted, stirring after each min. Stir in pecans. Pour into crust.
MICROWAVE chocolate in medium microwaveable bowl on HIGH 1-1/2 to 2 min. or until chocolate is completely melted, stirring after each min. Add 2 cups of the whipped topping; stir with wire whisk until well blended. Spread evenly over caramel layer in crust.
REFRIGERATE at least 2 hours. Let stand at room temperature 10 to 15 min. before serving. Top with the remaining whipped topping. Store leftover pie in refrigerator.