Meanwhile, microwave 3 oz. chocolate in microwaveable bowl on HIGH 2 min. or until melted; cool slightly. Mix cream cheese and remaining icing sugar in medium bowl until blended. Add melted chocolate; mix well. Gently stir in 1-1/2 cups Cool Whip
. Microwave remaining chocolate and Cool Whip
in separate microwaveable bowl on HIGH 45 sec.; stir until blended.