Pour one gallon of milk into a large pot and stirring constantly, slowly bring just to a boil. Turn off heat and allow to cool to a warm room temperature. (I used Vit D whole milk. Do not allow milk to scald, the longer it takes to bring to temperature the more water evaporates from the milk. The less runny your yogurt will be. )
Add one tablespoon of any plain live active culture yogurt that is room temperature. Stir into milk. (I added in vanilla for flavor at this point as well.)
As soon as the yogurt is stirred into the milk, pour into containers. (For convenience I poured the yogurt into recycled containers to set up. Instead of scooping the set up yogurt into containers later. Later I plan on using wide mouth glass jars that can easily be sterilized.)
If you keep your house fairly warm you can let the containers sit on the counter overnight covered. Our house is cool so I turned the oven setting to warm 100F and let them sit covered and undisturbed in the warm oven for 12 hrs. 100F is the ideal temperature for the yogurt to cultivate.
This is what it looks like 12 hours later! The yogurt is finished and I placed them in the refrigerator.
Delicious!!! I added a small amount of honey to my yogurt when it is in individual dishes. Purchased yogurt has a date of a month and a half stamped on it from the date I purchase it. I am going to use this time frame as an approximate expiration date for my yogurt watching it closely. I honestly don't think we will have any left that long :) Happy yogurt making!!!