Yogurt!

If you like eating yogurt, you should certainly try making your own. You can make delicious and varied styles of yogurt for the cost of milk, and it can be used in many meals and recipes, either as a stand-alone (as for breakfast or dessert) or as a beautiful replacement for sour cream on tacos or in scones, for instance. Yogurt-making is rewarding and  not very difficult, but you need one thing that many people don't have readily available: the ability to incubate something at body temperature (99 F or 37 C) for 16 hours or so. I happen to have an oven with a pilot light in it, and it happens to stay very close to 99 F when it is turned off and I'm not using the range. Even if you have an electric oven or an electric ignition gas oven, you may be able to make it work. Some ovens have a "proof" setting but this is variable; it is generally around 100 F but can be 85-115 depending on the model. Too cold, and your yogurt culture won't thrive; too hot, and it will die. If your oven has a light, you can keep the light on and this will provide a very gentle heating. Test your oven by placing a glass of water in the oven in a particular location and let it sit overnight. Test the temperature the next morning. If it is more than 5 degrees off of 99, try something different. Place the glass closer to the light, or further away, or move the rack up or down. Once you find the perfect conditions in your oven, congratulations! You're ready.
This recipe calls for one quart of milk. You can not double the recipe unless you extend the incubation time or you have access to an automatic stirrer. This is biology at work! Yogurt develops as the culture thrives, the Lactobacillus sp. bacteria (yes they are bacteria), and the sixteen hours of incubation here is for one quart of milk. Doubling the milk will not necessarily double the incubation time, but if the culture is not continuously stirred the bacteria will not have enough time to convert all the milk to yogurt, and you will waste milk. You can tell if milk was wasted by looking at the "whey" in the bottom of the straining container. If it is relatively clear, you have strained out water and have not lost much milk protein. If it is milky, well, that's milk. By the way, you can use any milk for this, whether cow's, sheep's, or goat's, but I use cow's milk (as fresh as I can find, organic if possible) as it is the easiest to find and the least expensive. Also, this recipe calls for a 16 hour incubation and 12 hour straining time. I find that it's most convenient for me to start the whole process around 2 pm, incubating by 3 pm, straining by 7 am the next day, and finishing by 7 pm. The 12 hour straining produces yogurt that is very thick, like ice cream though it is not frozen. One of my favorite preparations is simply to drizzle a little honey on top. For something special, this can be combined with some fresh berries and freshly toasted seeds (such as sunflower, poppy, and sesame) on top. On to the recipe:

1 quart (1 L) milk
2 Tbsp yogurt culture (you can use any yogurt that you like and which contains live culture; after one batch of yogurt you can keep yours going forever. I like the culture in the Greek yogurt Fage)
Cheese cloth; at least one yard (1 m), double-thickness

Mix 2 Tbsp milk with your yogurt culture. Set aside. Place remaining milk in a saucepan and bring to boil, stirring occasionally in order to prevent burning. Once milk boils, remove from heat and allow to cool down until it reaches a temperature of 99 F (37 C). Monitor the milk temperature carefully, this is science. When the milk is at the correct temperature, make a hole in the skin that has formed on top and pour in your yogurt-milk mixture. Place the pan in the oven-incubator so that it stays at 99 F for 16 hours.
After the incubation, the milk should have a pleasant aroma, not like spoiled milk. Place a large strainer or pasta colander over a medium pot. Lay on cheesecloth until you have three layers and the colander is covered. Carefully pour in the warm milk mixture, scraping the saucepan clean. Place the colander and pot in a refrigerator; refrigerate for 12 hours for thick yogurt that is the consistency of ice cream. Strain for fewer hours for thinner yogurt.