STIR drink mix and water in large bowl until mix is dissolved. Add ice cream; beat with electric mixer on low speed until well blended. Gently stir in whipped topping. Freeze, if necessary, until mixture is thick enough to mound.
SPOON into crust.
FREEZE 4 hours or until firm. Remove from freezer about 15 min. before serving. Let stand at room temperature to soften slightly. Store leftovers in freezer.