[evilelectron]

How I do it:

  1. Heat 14oz of milk for 2 minutes in a 700W microwave
  2. Add 4oz of cold milk to a container
  3. Add 2 spoons of Yogurt (I use Pavel's full cream) to the cold milk and mix
  4. Pour the hot milk in the container and stir it
  5. Put away in a place where the temperature won't fluctuate much and container won't be disturbed for next 12-18 hour. 
     I use an oven for this with no per-heating or temperature control.