Add one quart of whole milk into a medium-sized saucepan and heat it over medium heat until it reaches 182 degrees Fahrenheit. Make sure to stir intermittently so it doesn't develop a skin or burn on the bottom.
Once you've hit your temperature, remove from the stove and let it cool down to 115 degrees Fahrenheit. Take 3 ½ tablespoons of store-bought yogurt that has live and active cultures and mix it with one cup of your warm milk. Pour that mixture back into your pot and give it a good stir.
Make sure your mixture does not drop below 110 degrees Fahrenheit.
Take your mixture and pour it into two pint-sized jars; lightly covering it with a lid. Place the jars in a warm area that's about 110-115 degrees Fahrenheit. To do this, you can wrap your jars in towels and place them in the oven with the light on. Let these sit out for 6-12 hours to let thicken.
To make a Greek yogurt, take a strainer lined with cheesecloth and pour your mixture through it. Let it drip for one hour in the refrigerator.
