In a large crock pot, pour 1/2 gallon of milk (8 cups)- you can use any kind- I used skim, but just make sure it is not ultra-pasteurized (apparently that kind does not work). Mine was just regular skim grocery store milk. I also mixed in 1 c. nonfat powdered milk. This makes it creamier.
Turn it on low and cook for 2 1/2 hours. (If your crock pot cooks lower or heats up slowly, start it on high for an hour then turn to low for remaining time) After it has been cooking a total of 2 1/2 hours, turn off the crock pot. Let it sit for 3 hours to cool.
Put the lid on and wrap a large towel around the whole crock pot. Let it sit for 8-10 hours- or overnight. When you open it in the morning it should be thick and creamy.
You can use this as a substitute for sour cream, you can mix in any flavoring that you like- honey, sugar, vanilla, jam, fruit, etc. I am planning on making some frozen "go-gurt" pops for my kids. I mixed in some strawberry jam and I am putting it into little snack-sized Ziploc bags then freezing. We also did some with a chocolate pudding mix stirred in. Should make for a tasty treat! The flavor possibilities are endless...