Oven with a working light you can leave on overnight.
4tbspof yogurt with active cultures(to use as the starter)
Fill the 2 cup glass measuring cup with water and microwave until it comes to a boil.
Sterilize all equipment to be used by submerging in boiling water for one minute. Use only sterilized equipment for the remaining steps.
To sterilize the stockpot, wash fresh with HOT soapy water.
Run an ice cube around the inside of the pot to facilitate cleanup, see notes.
Heat the Milk
Add the milk to the pot, attach the candy thermometer to the side of the pot, and heat the milk to 180°F.
Turn the heat to low and hold at 180°F for at least 5 min.
Remove the pot from heat, and let sit, stirring occasionally, until the temperature reaches 115°F.
Inoculate the Culture
While the milk is cooling, pull the 4 tablespoons of starter yogurt out, transfer to the now-empty 2 cup measuring cup, and let sit out to come to room temperature.
Once the milk reaches 115°F use ladle to transfer about 1 cup of milk to the measuring cup with the starter yogurt, and whisk well.
Transfer the milk/yogurt mixture back to the large pot with the rest of the milk, and mix well.
Place the lid on the pot, wrap in a towel, and put in the oven with the light on (use the proof setting if you have one), for 6-12 hours. Longer will result in a more tart flavor, so you can control this based on your preference.
Remove the pot from the oven, uncover, and let cool slightly (20-30 minutes).
Ladle off any whey that has collected on the top - save if wanted.
Transfer the yogurt to a lidded container, and chill in the refrigerator for ~8 hours.
Make it Greek Style
If you prefer a thicker Greek style yogurt, strain in a nut milk bag for at least 2 hours in the fridge, until desired texture is reached.
Whisk well to smooth out the yogurt, and enjoy!
If you are using a stainless steel pot, Cheryl recommends rubbing an ice cube around the inside of the pot before adding the milk. Absolutely do this! I can attest that it makes cleanup much easier. I’m not sure why this is, but the science nerd in me thinks that likely the cold ice cube is closing off any “open molecules” in the pot, that would otherwise bind to the milk and create a tough residue on the sides of the pot. Maybe??Before starting, I sterilize all the tools I will use with boiling water, just to be safe.Don’t forget to save 4 tablespoons of your finished yogurt to use as the starter in your next batch!If you strain the yogurt to make it thicker, save the whey! There are several "ways" it can be used, which I discuss here.