In a large heat-resistant bowl, dissolve gelatin in boiling water. With wire whisk, stir in then yogurt; with a wooden spoon fold in whipped topping. Transfer mixture to prepared crust; refrigerate overnight or at least 2 hours. NOTE: This can be made with sugar free gelatin and light yogurt if desired. I have also used on one container of yogurt and was just as good. Can also change gelatin flavors and the yogurt flavors.