I started making yogurt again a couple months ago. Years ago, when we had milk cows and the boys were all home, I made yogurt by the gallon for a couple of years. Usually we had it with granola and added homemade jams for sweetener. I stopped making it when I started working, and the cows were gone around the same time.
A couple people asked about how to make it. There are several tutorials online for the process. I can show you, though, how I do it.
First step is to heat the milk to 180-185 degrees. I use 2% milk, but you can use whole and probably skim too. I use a candy thermometer for measuring the temperature, and I also use a double boiler because milk will scorch quickly if it's not stirred constantly while heating. I was lucky enough to find my double boiler at a consignment shop for a couple dollars, and I have also seen them on eBay for reasonable prices. Put water in the bottom of the double boiler, milk in the top. I use about 2 quarts of milk for each batch.
While the milk is heating, the jars need to be washed and sterilized. I heat water to boiling and pour it in to the jars. I put the lids in a pan and bring them to a boil too. I have a variety of small jars I use, including jars that once held things like marinated artichokes. These have to be very, very clean--any residue of pickling liquid or spices will ruin yogurt. For this batch, I just used my half-pint canning jars. I re-use old lids, since they don't have to seal, they just need to keep the yogurt for slopping out.
I stir the milk off and on while I'm getting the jars ready, and as the temperature gets higher, I stir it almost constantly, probably the last 2 or 3 minutes. When the temperature has reached 180-185 degrees, I take it off the stove, remove the bottom part of the boiler and pour off the boiling water. Then I refill the pan with cold water and put the top part back on it so that the milk will cool more quickly.
When the milk has cooled to 110 degrees, I stir in some already-made PLAIN yogurt. This is the culture, and if you use store-bought yogurt make sure the label says something like this:
You need that active culture for your yogurt to thicken. I use an old hand mixer for this, but a whisk or fork would probably work too.
Then the yogurt is ladled into the sterilized jars, the lids are put on and tightened, and I put them into a pan of very hot tap water.
The next step depends on your house. I am able to use my oven to culture the yogurt because my pilot light is always on and the oven stays at the perfect temperature--around 110 degrees. So you need to find a place that works in your house. I have heard of people using crock pots with hot water in them, and just turning it on every so often to keep the temperature even. Keeping the jars in a pan of hot water works for others, but you'd need to keep the temperature even. A sunny window on a warm day might also work. I've wondered about a heating pad--putting it under or around the jars. I'm sure there are many other creative methods of doing this.
The yogurt needs several hours to be thick and ready to eat. I usually make mine in the evening and by the time we get up in the morning it's ready. Generally expect it to take 4-8 hours to thicken.
When it's ready we put it in the fridge. I like mine sweetened and usually add some homemade jam to the jar before eating (this jar has pear conserve added--yum!). Larry prefers it plain, and says it reminds him of buttermilk.
That's all there is to it--a lot of hurry up and wait, as my mother would have said. But the end result beats anything you will get at the store, hands down.