(I used whole milk)
1/4 cup plain yogurt with active cultures
In a heavy-bottomed 4-quart saucepan, heat milk, stirring frequently over medium heat, to 185 degrees. Remove from heat, and let cool to 110 degrees. Place yogurt in a medium bowl. Using a whisk, gradually stir in cooled milk, about 1/2 cup at a time, stirring until smooth between additions. Cover the bowl with plastic wrap, poking two or three holes for ventilation. Transfer to a warm place (about 90 degrees) . Let sit until milk begins to thicken around the edges and the yogurt is set, about 4 - 6 hours. I place mine in the oven and leave the oven light on or I place it in the microwave oven. Yogurt will be "done" in 4-6 hours but you can let it incubate for up to 12 (on the counter at room temperature) depending on how tart you like it and how much beneficial bacteria you wish it to have. Place in a covered bowl in the refrigerator until completely set and chilled. Reserve at least 1/4 cup of this yogurt to begin next batch. Refrigerate for up to 2 weeks in an airtight container.
Suggestions for flavoring plain yogurt:
Use fresh strawberries, blueberries or peaches, granola, peach or cherry pie filling, or stir in plain vanilla, freezer jam , regular jam or fruit preserves or even applesauce. You can even take about 1 - tsp of flavored jell-0 (I like strawberry) and mix it in with about a cup of yogurt.There is no rule here so just experiment.
*If you want your yogurt thicker (like Greek Yogurt), line a fine strainer with a coffee filter. Scoop the yogurt into the filter. and the excess water will come out of the bottom. When it is as thick as you want add the yogurt back to the container.