Equipment needed: Thermos flask (one with a wide mouth is easier to spoon out/clean etc) Pan Thermometer (optional) Method: 1. Gently heat the milk to boiling point (above 86c) 2. Take off heat and let it cool to 43c 3. While it is cooling, fill the flask to the brim with boiling water for at least 5 mins to sterilise and pre-heat the flask 4. When the milk is the right temperature (too hot and it will kill the bacteria, too cool and they won't grow!) add the 1 tablespoon of live yoghurt and stir well 5. Empty the water from the flask and pour the milk mixture to the flask. Seal, then place in a warm place. You need to keep a consistent temperature so in cold weather you might want to add extra insulation such as wrapping it in a dry tea towel. I don't have an airing cupboard so I just found the warmest room and left it there 6. Leave it overnight, in the morning you should have fresh live yoghurt! 7-8 hours is about right You may also want to reserve a tablespoon of yoghurt to use on your next batch. Put into a sterilised pot and freeze. Defrost before using.