This is not going to save you enough money to take the family to Paris for the week-end or anything, or not quickly at any rate, but it is quite fun. There’s something nice about knowing that once you’ve made the first batch of yoghurt, with luck, a following wind and an endless supply of milk you can keep making new from old, which is quite satisfying.
Anyway, the point of buying the above yoghurt maker is that it keeps the starting culture and the milk at a nice constant temperature. It’s like a propagator I guess. You just put a couple of teaspoons of super fresh , natural, unflavoured yoghurt (shop bought the first time, then you can just use the last of the previous batch) and a load of milk (UHT works best) into the central container, put the lid on, switch on the power, and watch like a hawk for 8 hours. Or go to bed, up to you.
So far I’ve had very consistent results. Then comes the creative part. You hang the whole lot up in some muslin or something from the nearest door handle for a few hours, and Bob’s your Mother’s Brother, Greek yoghurt! Genius.
If you don’t want to spend money on a yoghurt maker, the alternative is to control the heat manually. You could put your yoghurt and milk mixture into a very very low oven, 40°C or so; or into an airing cupboard, on top of a radiator, under a chicken? Or you could even put the mixture into jars in a pan of water on very low heat for half the day. All of these will work fine, so long as the temperature remains more or less constant.