Buy a quart of organic whole milk yogurt and freeze it in ice cube trays. Take 4 cubes (1/2 cup) out and let them defrost during the afternoon. That evening heat 4 cups milk to 180 and then cool to 110, add the thawed room-temp yogurt, stir and place in a glass pyrex, cover lightly and place in oven set to "warm" overnight. In the morning it is nice and firm. Put the lid on the dish and put in the fridge. I add a couple drops of vanilla creme liquid stevia to each serving when we eat it... very yummy!