01 - Pour the milk into a saucepan and warm gently over medium heat, stirring occasionally, until it reaches 185°F (85°C). Do not allow the milk to come to a boil.
02 - Remove the saucepan from heat and let the milk cool to between 110°F and 113°F (43–45°C).
03 - In a small bowl, combine the yogurt starter with a few tablespoons of the cooled milk, whisking until smooth and fully blended.
04 - Pour the starter mixture back into the remaining cooled milk and stir thoroughly to ensure even distribution.
05 - Divide the mixture into a clean container or individual jars. Cover loosely with lids or a clean towel.
06 - Place the containers in a warm spot — such as a turned-off oven with the interior light on or a yogurt maker — and incubate for 8 to 12 hours, until the yogurt reaches your preferred thickness and tanginess.
07 - Transfer the yogurt to the refrigerator and chill for at least 2 hours before eating. Store refrigerated for up to 1 week.