Place the milk in a pot and heat to 180F degrees, whisking regularly to prevent it from scalding and sticking to the pot.
Once it's at 180F degrees, remove the pot from the heat and place in an ice bath to cool to 110F degrees.
Once at 110F degrees, whisk in the Greek yogurt.
Pour the mixture into either cleaned 4 ounce balls jars for individual servings, or larger balls jars, as long as they have lids.
Tighten the lids "finger tight," or tight just to where your finger tips feels the lid grab the threads. *Don't overtighten or your jars may crack under the pressure. Don't leave too loose or water can get into your jars. You'll feel it when it's right.
Place the jars in the sous vide water bath and cook for 12 hours. If you like less tangy yogurt, cook for only 8 hours, and more tangy you can cook up to 24 hours.
Remove the jars from the water bath and wipe the moisture off them.
Store in the fridge overnight to fully cool.
For extra thick yogurt, you can strain it through cheesecloth to remove any extra moisture.
Otherwise, serve it garnished with drizzled honey and fresh fruit.
Notes
Use a good quality pasteurized whole milk for the best flavor results.
Do not use raw milk as it can contain unwanted bacteria that can make you ill.
You can use regular yogurt instead of Greek yogurt, as long as it has cultures.
Heat the milk per the instructions as it will kill any bacteria and give you a thicker creamier result.
You can also heat the milk in the sous vide bath at 180F degrees if you don't want to worry about boiling it over. It will take longer and you will need to cool the bath down to 110F or 115F before putting the yogurt back in.
For a thicker yogurt, cook at 115F degrees.
For a thicker, tangier yogurt, cook up to 24 hours.
For a less tangy yogurt, cook for 8 hours.
The yogurt can be strained through a mesh strainer and/or cheesecloth if you want a thicker yogurt.