Milk (however much you need) I like to use organic 1%, but you could use any.
Yoghurt starter — I used freeze dried L. bulgaricus, S. thermophilus, and L. acidophilus, but you can also use 2 to 3 tbsps of plain yoghurt, apparently. I shall experiment with this method and post the results.
Heat up your milk slowly–I used approximately 2 cups–until a skin forms. Turn off the heat and let it cool down. Remove the skin. You can put the pan in cold water if you’re in a hurry. While you’re doing this, turn the oven on to 170 F and heat up a bowl or appropriate size to hold the yoghurt mixture. Turn off the oven and leave it to cool down a bit and take out the bowl.
When the milk is lukewarm, mix a little of it with the yoghurt starter powder (or plain yoghurt if you’re trying that). If the bowl is cooled to the touch, but still warm, pour the milk/yoghurt starter mixture into the bowl. Wrap in a cozy tea towel (not too thin) and put in the now lukewarm oven. Leave it there for anywhere from 7 to 24 hours; then refrigerate it. It should be thick enough to hold its shape when spooned out. Lovely, and a lot cheaper than the $5.99 a carton they’re charging in the stores now!