ADD boiling water to gelatin mix in large bowl; stir 2 min. until completely dissolved. Add enough ice to cold water to measure 1 cup. Add to gelatin; stir until slightly thickened. Remove any unmelted ice. Whisk in 2 cups COOL WHIP until well blended. Refrigerate 30 min. or until thick enough to mound.
SPOON into crust. Refrigerate 4 hours or until firm.
TOP with remaining COOL WHIP just before serving.