This is my Yiayia's recipe and we had it every day. We started milking the sheep around Christmas time when the ewes first gave birth, and we continued milking until May. Out of habit, I still dip my finger in to test the temperature (but you don't have to!) and the longer you let it set, the more sour the yogurt becomes. Adjust to your taste, and add any topping you'd like!
1 gallon whole milk, any fat content is permissible
3-4 tablespoons of active live yogurt
1) In a large pot, heat milk on medium-high heat, stirring often with a wire whisk to prevent burning until the temperature reaches at least 185 degrees Fahrenheit, remove from heat, and set aside uncovered.
2) Check the milk temperature repeatedly until it cools to between 110-115 degrees Fahrenheit, in about 40 minutes to an hour.
3) Make a slurry of the active live yogurt and about a cup of the hot milk.
4) Stir this slur into the hot milk and stir well with a wire whisk.
5) Cover the pot, and maintain a temperature of between 110-115 degrees for four to six hours until a custard consistency forms and you can see the milk separate into a solid curd, and a clear, liquid whey.
6) The temperature can be maintained by wrapping the pot in a towel and placing in a warm room, or by placing it in the oven, with the oven light on. Resist the urge to check the yogurt too often while it cultures.
7) The longer you culture the milk, the more sour the taste, and firmer the curd,
8) Leave to set.
9) Line a large colander or sieve with cheese cloth, and place it over a large pot to collect the drain clear whey liquid. Pour the yogurt into the colander and place it in the refrigerator for 4-6 hours to strain.