Add the heavy cream to a medium size saucepan and heat slowly, on a low flame, with a thermometer inserted in the liquid to measure its temperature. I set the timer for 10 minutes at the beginning and after that I check it every 3 minutes or so. When the liquid reaches about 160 degrees F, I hover over the pan to catch it just as it is reaching 180 degrees F (it's a steady simmer, not a boil).
Next, let it cool to room temperature. You can speed up the cooling process by placing the pan in an ice water bath.
Once the liquid is at or close to room temperature, add the yogurt starter to my yogurt container (I use a glass container). Remove the film from the top of the pan with a fork, and then pour the liquid into the yogurt container and stir to dissolve the starter.
Next, place the yogurt container in the yogurt maker, and let the magic last for 24 hours. I set a reminder in my email/calender application to take the yogurt out the next day.
Finally, place the yogurt container in the refrigerator for about 8 hours.