Step 4: Keep the yogurt warm and undisturbed
Wrap the slow cooker (lid on) in a thick towel and put it in the oven with the light on.
Boil some water in the tea kettle or pot and put that in the oven too. This keeps my oven at a perfect 100 degrees.
Let this sit undisturbed for 6 to 12 hours, depending on how tangy you like your yogurt. I do 8 hours.