1 galwhole milk 1/2 c milk, powdered 1 c yogurt - natural plain
Pour milk into large pot and start warming up.
Add very hot tap water to gallon milk jug and place in cooler (where it will incubate the yogurt as it sets). Put lid on cooler and let warm up.
Warm milk and powdered milk to 180 degrees (use a candy thermometer). Cool rapidly to 130 degrees (place pot with warm milk in ice water to cool).
When cooled add plain yogurt and stir well to mix.
Carefully pour into 5 sterile canning jars and put lids on top.
Carefully place jars in cooler, (I replaced hot water with a new container of very hot water here) cover with towel and then cover with cooler lid. Put in a room where it will not be disturbed.
Let sit 5 to 7 hours (the longer it sits the thicker it is) and then place in refrigerator.
Add vanilla to taste if desired when serving.
It is also good with honey and cinnamon or blended with fruit.