To Make Yogurt
• Heat a scant 4 cups of whole milk to 185ºF (85ºC). Cool to 105ºF (40ºC).
• Meanwhile, place 4 tablespoons of plain, whole-milk yogurt that contains live and active cultures in a quart jar. Cover.
• Once the milk has cooled, pour it into the jar and stir to mix the yogurt and milk together.
• Screw on the lid firmly and place the jar in a crockpot. Fill the crockpot with water and turn to “warm” or the lowest setting.
• Check the yogurt after 6 hours. Gently tilt the jar to see if it is set to your liking.
Once the yogurt is fully set, place in the refrigerator to cool completely.
To make Greek yogurt:
• Place a colander in a large bowl. Line the colander with cheesecloth, thick paper towels, or a clean tea towel.
• Pour the yogurt into the cheesecloth-lined colander and fold the cheesecloth on top.
• Place a small plate over the cheesecloth and put something heavy (like a stack of bowls) on top.
• Put the whole thing into the refrigerator for a few hours.
• Discard or save the whey and scrape the yogurt into a storage container.