Pour half a gallon of whole milk into a heavy bottom pot
Turn burner to medium-high heat and slowly increase to medium-high, stirring continuously for about 10 minutes
Heat milk until it reaches 180°F or until small bubbles form around the edge of the pot
Cool the milk down to 120°F by running cool water over the pot or using an ice bath, then let it sit uncovered for a few minutes
Remove the scum from the top of the milk
Mix 4 tablespoons of yogurt starter with a few ladles of the warm milk
Pour the yogurt mixture back into the pot and stir to evenly distribute
Cover the pot with a lid and tea towels
Place the covered pot in an off oven and let it sit undisturbed for 8 to 10 hours
Place a colander over a bowl and line with a flour sack towel or cheesecloth
Pour the yogurt into the lined colander and refrigerate for 2 to 4 hours to reach desired thickness
Save 4 tablespoons from each batch as starter for the next batch
Store finished yogurt in mason jars in the refrigerator
