Pour 2 tablespoons of milk* into a small dish and set aside. In a heavy bottomed pan or a double boiler set a candy thermometer or instant read thermometer, pour in the balance of the milk and heat over medium heat. Stir constantly; watching it closely so you don't burn the milk.
Heat the milk to 180º F, stirring constantly, watch don't allow it to boil. Once reached 180º F, immediately remove the pot from the stove and carefully pour the hot milk into a glass mixing bowl or ceramic (not metal) bowl, even a deep casserole dish would work.
Place the dish on a cooling rack, UNCOVERED and allow the milk to cool to between 105° and 110°. In the middle of summer, this took about 45 minutes. Make sure leave the dish/bowl uncovered, allowing for the good bacteria to expand.
Once it's close to the 110-105° turn your oven to it's warm or "proof" setting if you have it, or heat to 150º.
Combine 2 tablespoons of reserved milk and 2-3 level tablespoons of plain yogurt and stir to combine. I used 2 ½ tablespoons of yogurt. Make sure yogurt is plain and has live and active cultures in it! I used Noosa plain yogurt. Resist the urge to add more than 3 tablespoons of yogurt, see notes in blog post.
As soon as your milk has cooled to 110-105º, using a non-metal spatula or wooden spoon, stir in your milk/yogurt starter mixture into the milk. Stir well until combined. Note | a film might develop while your milk cools, just stir it in.
Place the lid on your bowl (or cover with plastic wrap), carefully wrap the covered bowl of yogurt mixture in a heavy tea towel or I used an old clean bath towel and place the towel wrapped, covered dish in the oven.
IMPORTANT STEP...turn your oven off, but turn the oven lights ON. The heat from the light of the oven should be enough to keep the dish warm enough to permit the yogurt-making process (i.e. bacterial process). Leave the yogurt alone for 7-8 hours or overnight.
TIP | Make sure that your towel isn't near the oven lights. Try to not disturb the yogurt during it's bacterial phase!
In the morning, carefully take your dish out of the oven, unwrap the towel and remove the lid, check to see whether the milk has turned into yogurt, it should be thick and creamy, especially if you used whole milk. If your batch hasn't quite thickened, return to the oven and check in an hour.
If just want regular yogurt, you can stop at this stage, just stir and refrigerate, it may develop a little watery liquid, that can just be poured off before serving, but if you are going for creamy, dreamy, thick Greek yogurt, move on to the next step.
Refrigerate the yogurt (without stirring) for at least 3 or more hours until completely cooled and further thickened.
Then line a large mesh strainer with 4 layers of dampened cheesecloth (I wet mine, then squeezed it out with my hands and laid it in a cross pattern, setting the lined strainer in a bowl large enough to allow the strainer to drain and not sit on the bottom of the bowl.
Refrigerate for one hour, then pour the liquid that has puddled in the bottom out, discard. Return the strainer, yogurt and bowl to the refrigerator for one more hour (if desired), strain the liquid again and your yogurt will be done! Spoon or pour your yogurt into a container (makes about 32 oz; reuse a clean yogurt container or a glass container fitted with a lid).
TIP | If you think you might make additional batches of homemade yogurt, reserve 2-3 tablespoons of your yogurt as a starter for your next batch. Keep tightly covered in the fridge until ready to use. Refrigerate for up to 6-10 days.
HONEY VANILLA BEAN YOGURT
If you prefer your yogurt a bit sweeter, stir in a scant ⅛ - ¼ cup of honey; raw, local honey is best! Stir in 1 teaspoon of Vanilla Bean Paste along with the honey, until combined.
Refrigerate until ready to eat. Try making a yogurt parfait by layering fruit, granola and yogurt.
Notes
* Higher fat content of the milk will yield creamier yogurt, all yummy though, see notes in post.