cover bottom of large pan with water 1/2 cup bring to boil

add 1 gal milk turn heat down to med

heat milk to 180 - 190°F

turn heat off and cool to 110 - 120°F

in small bowl stir warm milk into yogurt then add it to the big pan of milk

put lid on pan and cover with towel put in oven with only the light on for 5 hours

or put into small containers cover with towel place in oven 5 hours

refrigerate good plain or with honey, jam, or fruit