You will quickly learn that I don't like to follow recipes much, I tend to change them often, and substitute what's in the 'fridge at the last minute. So, when I originally read about this, it asked (I think) for whole or 2% milk. All I had at the time was 1%, so that is what I used then, and pretty much have been using... although there was one time that, on a whim, I threw in a cup of cream...
1qt milk (whatever percentage is available)
2T yogurt starter or store bought yogurt (Yogurt starter can be gotten at any health food store. As for the store-bought yogurt, it should be plain yogurt--no flavors, not even vanilla.)
Place milk in saucepan and heat over low heat until bubbles form at edges and steam rises from the middle. Do not allow to boil. Transfer to large bowl. Allow to cool to 110-115F on a cooking thermometer. Don't have one? Nor do I--just get it to a temperature where you can stand to keep your index finger in the milk for 20 seconds.
Place the starter or yogurt in a small bowl, and add a few tablespoons of the warm milk. Stir well, and return to the rest of the warm milk a small portion at a time, stirring well with each addition.
Cover with a heavy towel and keep in a warm place at least 6 hours, or overnight. My kitchen tends to be cold in the winter, so I preheat my oven to 200F, turn it off and place my mixture in the oven for the allotted time.
Now, cover with plastic wrap, and place the yogurt in the 'fridge for at least 8 hours before serving. I like a very thick yogurt, so I strain it through a cheesecloth in a fine sieve suspended in a bowl for another 6 hours or so.
Yes, it takes a long time--about a whole day, but it is not at all work-intensive. And the reward is well worth it!! Now, you can eat your yogurt as-is, mix with marmalades, fresh fruits and cinnamon, place in crepes (mine is VERY thick), the possibilities are endless.
Eat well :)