I discovered this process about three months ago. It’s incredibly simple–only about ten minutes of work, really. I haven’t really made it scientific yet, but here are my approximations. It’s really simple and it really works. The taste? Pretty darn decent. The convenience? Incredible. The uses for plain yogurt? Countless . . .
For app. 2 quarts of yogurt:
2 c. powdered milk
2 c. hot water (123 degrees F or 50 degrees C or hotter–this temperature feels hot but does not burn you)
1/2 c. plain yogurt (either purchased or reserved from last batch of yogurt)
an instant-read thermometer ($6 at Target)
In a blender (or a mixing picture), mix the powdered milk and the hot water until smooth (if your powdered milk has lumps in it, your yogurt will too). Pour into a large glass jar (I bought mine at Target), and add enough water to fill the rest of the jar. (My tap water is about 127 degrees F, so I just let it rest a couple of minutes–if your tap water isn’t that hot, you could microwave it briefly.) When the mixture has reached 123-124 degrees, add the yogurt and stir with a wooden spoon. Cover with plastic, and wrap with 3-4 towels, and leave undisturbed on your counter. About 8 hours later, you’ll have yogurt.
At this point, take 1/2 c. out (to save for the next batch), and flavor the rest with honey, sugar, vanilla, jam, fresh berries, etc. If you want greek-style yogurt (creamier), you can place the yogurt in a colander lined with 4-5 layers of cheesecloth, and let it drain for 2 hours. Then, refrigerate.
If you don’t have powdered milk, you can use regular milk, but you have to boil it first (to kill a bacteria that somehow prevents yogurt from happening), and then let the boiled milk cool to 123 degrees and then proceed as directed above. (It’s critical to not add the yogurt before the milk gets to the proper temperature or it will do something horrible–like die.)
You could also half this recipe and make it in a large quart mason jar, if you don’t need 2 quarts every week 🙂