Bring 4 liters of fresh whole milk to the boil briefly and then let cool down to lukewarm.
Now remove some milk and mix it with 1 1/2 tablespoons of Greek yogurt. Add this milk to the other milk and leave the pot wrapped in a blanket for several hours.
I do it in the evening and leave it overnight.
Then drain the yogurt in a cloth until it has a firm consistency.
You can either eat the yogurt straight or use it for tzatziki.
It makes a decent amount, but it can be kept very well in the refrigerator.
I once gave the recipe for 6 people, but we also take the amount for 2 people.