Ingredients
1/2 gallon milk
1/4 c yogurt (with live cultures)
Tools:
pot for milk
thermometer (mine is a meat thermometer)
containers for yogurt with combined volume of 1/2 gallon (I use 2 old 1 qt yogurt containers from Stonyfield Farms)
big pot that fits your yogurt containers
towel or something you can wrap around big pot for insulation.
Preparation
divide yogurt evenly amongst your containers
heat milk in pot up to ~185 F
let milk cool in pot to ~110 F
pour milk into yogurt containers and stir to combine (combines better if you pour a little milk in to make the yogurt more liquidy and then add rest of milk) and put lid on.
heat water in big pot to ~110 F and take off heat
put milk/yogurt combo containers in big pot of 110 F water
put lid on big pot and wrap/cover with towel
wait 8-12 hrs (like overnight)