Homemade Yogurt

4 cups of fresh, organic 1% or 2% milk
1/3 cup of powdered milk (optional)
1/4 to 1/2 cup organic yogurt with live cultures 

Slowly heat the milk on the stove over low-medium heat. (You can choose to add powdered milk at this point; powdered milk creates thicker yogurt that takes less time to ferment.  It's optional if you are using whole milk or two percent.  Some skim and one percent milk include added milk proteins which make the product taste less watery and will behave the same way as if you added powdered milk.)  Heat the milk to 170° F, but not have it boil; then, remove from heat and wait for the milk to cool to 108-112° F.

When the milk is cooled to the proper temperature, mix a small amount it in with the yogurt, then mix all the milk and yogurt together.  Place in the warmed yogurt maker for 4-8 hours. Refrigerate before serving.  

Makes one quart.

From 101 Cookbooks blog