Since I'm lactose intolerant, I like to make my own yogurt. Commercial yogurt is only fermented 4-6 hours and contains lots of lactose.

Making yogurt is actually pretty easy.

You need:

1. gallon of milk (I use the organic house brand)
2. carton of commercial yogurt to use as starter (I use Fage Greek-style yogurt and ideally you want to use yogurt that only has milk and yogurt cultures in it and is free of other additives) It needs to be about 2 cups.
3. Stainless steel pot with a tight-fitting lid to boil the milk
4. Wire wisk
5. Heating pad
6. Meat thermometer (optional)

I put the heating pad on a kitchen towel on top of my fridge and plug it in. I find that the lowest setting on the heating pad works best.

I put the milk in the stainless steel pot and put it on the stove and turn up the heat. The key is to constantly stir the milk as it will boil over and make a huge mess if not carefully watched. After about 15-20 minutes on the stove, the milk will start to foam up which signals it is read to boil over. I turn off the heat and let the foam die down a bit and then turn on the heat again to make sure that the milk has boiled for at least a few seconds. This sterilizes the milk and prepares it to be inoculated with the yogurt culture/starter.

The next step is to put the milk into the refrigerator. The milk needs to cool down to about 100-110 degrees. At my altitude (I'm in Colorado) I find that it takes about 4 hours 30 minutes. YMMV.

Once the milk has cooled down, I put the starter into the milk using a clean spoon and gently stir it. I put the lid on the pot and put it on the heating pad. I then insert the meat thermometer between the heating pad and bottom of the pot to monitor the temperature. 100-110 degrees is best. Any cooler, and the yogurt doesn't ferment properly. Any hotter, and the cultures die.

To make sure the yogurt is lactose free, it needs to ferment at least 24 hours. I usually let it sit longer than that. The longer it sits, the tarter the yogurt tastes, which I happen to like. Sometimes my batches sit 32 hours or more.

After the yogurt has fermented at least 24 hours, put the milk back in the fridge. It needs to be cooled at least 8 hours before being eaten.

Any variety of milk can be used: skim, 1%, 2%, whole. The more milk fat the creamier it will be. I usually use 2%.

After the yogurt cools the whey will begin to separate from the yogurt. I usually toss it as it is kind of bitter.

For a real treat, you can strain off the whey and make Greek-style yogurt. I use a large coffee filter in a strainer. This makes the yogurt very thick and creamy, almost like a type of pudding.

Enjoy.