Since this summer, I've gotten into having smoothies on a regular basis. And yogurt is a key ingredient in my smoothie. The only option was "non fat" yogurt at my local grocery stores - I want a bit of dairy fat in my yogurt. So here's how to turn milk and cream into yogurt :)
Step 1: Ingridients
4 Cups of Milk
2 Cups of Cream (Half and Half works too)
4-5 Tablespoons of already made yogurt
A glass vessel that can hold about 6 cups of yogurt
Step 2: Sterilize
Mix Milk and cream in a pot and heat to 180 degrees - this will kill any extraneous bacteria that may be lurking. Be sure to mix frequently to prevent milk from burning on the bottom of your pot.
Step 3: Wait
Allow milk to cool down to 110 degrees. At the same time, put 5 tablespoons of yogurt in a cup, and allow it to reach room temperature.
During this time, it would be a good idea to clean your storage vessel(s).
Step 4: Oven and Yogurt
Set your oven to "Warm" mode. If it doesn't have a warm mode, let it preheat to 200.
Slowly bring your yogurt up to temperature (as not to shock any of the bacteria) - you can do this by adding a little warm milk, stirring - then adding more milk. Repeat.
Mix your yogurt into your milk for about two minutes to make a homogeneous mixture. Having it perfectly blended isn't super important, but it does speed the process along.
Then, pour your mixture into your glass storage vessel. Place in your oven (bottom rack) and allow to sit for about 4 hours. If you preheated to 200, turn your oven off once you've placed your container inside.
Step 5: 4 Hours Later
4 Hours later, check on your yogurt. Give it a slight tap and see check that it is firm to your liking. You can even take a sample taste if you want. If it's not firm enough, allow it to sit in the oven a little longer.
As I'm typing this, it shows the yogurt I made did not kill me.