Heat 3L of milk in a double boiler to 180 F then turn off and let sit for 10 min. (The temperature will still rise a bit but that’s ok.
Cool in ice bath until it reaches 110 degrees. Add a couple spoonfulls of yogurt and 4 drops rennet. Let sit 12 hours at 105 – 110 . Strain for 30 min. Whip.