Jello and yogurt are a classic combination, and I prefer this to the typical cool whip layer. I prefer to boil the water in the microwave - 2 cups take about 2 minutes. I also stick my jello in the freezer for 10-15 minutes so it sets faster between layers :). I use a plain tasting yogurt, so add 1/2 cup sugar, but you can leave it out if you are happy with the flavor of your yogurt. Cooking time is time to set in the freezer.