Use a big pot that can hold more than a gallon
Wet the pot to prevent it from burning
Pour 1 gallon of your favorite milk in the pot
Set the burner on low and bring the milk to a boil
Turn off the burner and finger test the milk until it's not burning but not warm (a happy medium)
Add 3 tablespoons of your favorite yogurt
Do not stir, put the lid on and move the pot to a quiet dark spot (like the oven) for 15-20 hours
Then move the pot to the refrigerator and leave it there for 5-6 hours (the longer in the fridge, the thicker the yogurt)
Scrap off the thick coagulation of cream on top and eat it like dessert, then put the remaining yogurt in containers