Homemade Vanilla Yogurt
I don't know why but I like making your basic kitchen staples from scratch. Cheese is next, but I thought I'd try yogurt first - probably the simplest thing at which to attempt inoculating dairy with bacteria.

This is adapted from a recipe found online:

-1/2 gallon whole milk, homogenized
-1 c. sugar
-1 T. vanilla
-a 7-ounce carton of greek yogurt

Combine milk and sugar in a heavy saucepan over medium heat. Stir continuously until sugar dissolves and milk comes to a boil. [This takes some time to stir, but it's important to ensure the milk doesn't burn on the bottom of the pan].
Once boiled, transfer milk to a glass or earthenware bowl. [I use the ceramic insert of my crock-pot slow cooker].
Using a thermometer, let milk cool to 105-110 degrees. This take about an hour.
Use a little of the warm milk to dilute and smooth out the real yogurt, which is acting as our "starter" since it already has all the beneficial bacteria, aka live cultures, that we need.
Cover yogurt with plastic wrap and set up on warm place for at least 4 and up to 12 hours. All this time depends on the tartness you prefer, but the yogurt at least need to "set", aka firm, so you know the cultures are active.
Refrigerate.
Makes 2 quarts.