Add 3/4 cup boiling water to lime gelatin mix in medium bowl; stir at least 2 min. until completely dissolved. Add ice; stir until gelatin is slightly thickened. Remove any unmelted ice. Pour into 1- to 1-1/2-qt. serving bowl. Refrigerate 15 min. or until set.
Stir remaining boiling water into strawberry gelatin mix in large bowl at least 2 min. until completely dissolved. Add 2/3 of COOL WHIP; stir with whisk until COOL WHIP is melted and mixture is well blended. Refrigerate remaining COOL WHIP for later use. Carefully spoon strawberry gelatin mixture over lime layer.
Refrigerate 2 hours or until set. Top with remaining COOL WHIP just before serving.