Slowly pour rennet mixture in a spiraling pattern over milk, stirring. Continue to stir for 3 to 5 minutes, using an up-down circular motion to distribute the rennet evenly. As you check the temperature, insert the thermometer gently to avoid breaking clot more than necessary. Next, to create crosshatch pattern and to release clear-colored whey, cut through solid clot to pan bottom with a long knife. From this point on, you need clean but not sterilized equipment.
Ladle curds into colander.
Let stand until curds stop dripping, about 1 hour. Each day, replace cheesecloth and discard whey. Testing the curd. If after 15 to 30 seconds the slice begins to soften and melt and, when held by 1 end, the piece stretches from its own weight, it's ready. If the slice doesn't stretch but tears, chill remaining curd, testing daily, up to 4 days.