When our milk arrives on Tuesday, I make yogurt for the week. Pieter has yogurt and banana for breakfast most mornings. I had never made yogurt before last fall and am amazed at how easy it is. My friend Shasta requested a little bit more details on this process, so here is my method. There are lots of posts on the web from other folks, so if this doesn't work for you, just search around for the best method for yourself.
This process for making yogurt can be used with the Bulgarian or Greek varieties of yogurt. The yogurt you would buy at the grocery store is almost always Bulgarian. I prefer the thicker Greek variety which I purchased from Cultures for Health. They also have great directions that are available to anyone on their website. One of the best tips I got from them was to culture in a non-reactive container, like a canning jar. They also only use wooden utensils, but I still just use a normal spoon.
Step 1: Heat up your milk to 160 degrees.
Step 2: Cool the milk to 110 degrees. This can be done in the same pan or you can pour it into the containers you will incubate the milk in. I prefer the latter method as it cools faster.
Step 3: Pour out most the milk from a container into another jar. Add 1 tablespoon of starter yogurt per 1 cup of milk. (You can use any plain yogurt as a starter if it has live cultures in the ingredients. Avoid additives in the yogurt, like sweeteners.) Stir well. Add the rest of the milk up to one inch from the top. Stir well.
Step 4: Cover yogurt and incubate the yogurt at 110 degrees for 5-7 hours. This can be dones in a variety of ways: a warm oven, in a covered slow cooker or pot with water at 110 degrees, or even a cooler. I use the slow cooker method and put a towel over the whole thing to keep the heat in. Every couple hours I turn it on for 5-8 minutes to raise the temperature back up to 110. I set a timer when I turn it on (I learned this after forgetting it on and killing all the bacteria). The yogurt is done when you tip the jar and the yogurt moves away from the jar in a single mass.
Step 6: Refrigerate for six hours to stop the culturing process.
Enjoy it, but don't eat it all! Save some for your starter to make your next batch of yogurt. You can now add any sweeteners or flavors to the yogurt you will eat. Our favorite is homemade vanilla.