Heat 4 cups of cow's milk on the stove. The ideal temperature is 82 degrees Celsius (a thermometer helps greatly). If you do not have a thermometer, simply bring the milk to a full boil, that will do the trick.
Let the milk cool to 43 degrees (110 degrees Fahrenheit).
Add 2 tablespoons of yoghurt in a clean jar large enough for the heated milk. This can be either store bought or from a previously made batch. You require the bacterial cultures in the yoghurt. Add a bit of cool milk from your fridge to the yoghurt and stir together.
Pour the heated milk into the jar. Be careful to not scald yourself in doing so. Cover the jar with its cap and wrap it in a towel if possible. The idea is to keep the jar as warm as possible for 8 hours. This allows the bacteria to work its magic.
This can be done by:
- Placing the jar in the oven and leaving the oven light on; 0r
- pouring hot water into a cooler and adding the jar into the water and closing the cooler.
After 8 hours, check to see if the yoghurt has thickened. Place the jar into the fridge when it has and enjoy cool, fresh and home made yoghurt when it cools!