Turn on your oven light only.
In a bowl, add in your yogurt and set it aside.
In a medium pot on medium high heat, add in the milk. Whisk occasionally while monitoring to make sure milk doesn't stick to the bottom. Whisk more frequently as it gets hotter. Bring milk to 200 degrees f.
Remove pot from the heat and allow it to cool to 115 degrees f.
Slowly add in 1/4 cup of the hot milk to the yogurt while whisking.
Add another 1/4 cup of hot milk to the yogurt slowly while whisking.
Whisk all the yogurt mixture into the rest of the hot milk in the pot. Mix well.
Place a lid on the pot and put it in the oven with the oven light on to keep the yogurt warm.
Leave in oven for 6-12 hours, pending on preference. The longer it stays the more tart and creamy it becomes. I personally like 7 hours.
You will know its done when you tilt the pot slightly and see the yogurt pull from the sides.
Whisk until smooth and add to storage container and set in the fridge for at least 4-6 hours before eating to thicken up and chill.
Once set, remove 1/2 cup of the yogurt for the next batch and place it in a separate container and use within 7-10 days for the next batch of yogurt.
Serve and enjoy!