Pour 1/2 gallon of milk into clean slow cooker (4 qt minimum size).

Turn slow cooker on low and let sit for 2.5 hours.

After 2.5 hours, turn off slow cooker and let sit (keep the cover on) for 3 hours.

After the three hours, remove 2 cups of the milk. Stir plain yogurt into the removed milk. Mix until completely incorporated. Pour milk/yogurt mixture into remaining milk in slow cooker. Whisk to combine.

Place lid on slow cooker and wrap with a large bath towel, let sit for 8 hours or overnight.

Your milk should have thickened and become yogurt! If you would like to thicken it more, place a few layers of cheesecloth or a flour sack towel over a colander. Place this in a bowl and pour the yogurt into the colander. Let drain for a few hours or until desired consistency is reached.

Don't forget to save 1/4 cup of your homemade yogurt for your next batch!