2 quarts of milk; skim, 1%, 2% or whole
of yogurt with active cultures
Pour the milk into a heavy saucepan and slowly heat to 180°F.
Turn off the heat and let the mixture cool to 115-120°F.
Remove 1/2 cup of the heated milk to a separate container; add the yogurt culture to the small amount of milk. Stir to mix. Add the yogurt/milk mixture back to the saucepan and stir to incorporate.
Cover the pan and wrap in a towel. Place in a turned-off oven; turn on the oven light for a little bit of warmth.
Let the mixture sit for 6 hours or overnight until desired consistency.