Cultured buttermilk is incredibly easy to make, keeps well for a week or so in the fridge, and really is wonderful in pancakes and baked goods. Making buttermilk is very easy. But it does require some advance preparation.
Some things you need to make buttermilk:
1. Buttermilk culture. I order from New England Cheesemaking Supply Company which has a user friendly website. Look in the "ingredients" section under cheesee cultures and mold powders. Once you have the culture, store it in your freezer.
2. A thermometer. I had thought I could use my candy thermometer with its handy clip, but then found that its dial starts at 100 degrees. For buttermilk you need one that reads accurately at lower temperatures. There is such a thing as a cheese thermometer, but I don't have one. So I use my meat thermometer and just keep dipping it in. Not as convenient as a thermometer that clips to the pan, but workable.
3. A clean mason jar with lid
1 quart whole milk (not ultrapasteurized)
1 packet (1/2 teaspoon buttermilk culture)
Heat milk in a medium saucepan until it reaches 72 degrees. Stir in the buttermilk culture. Transfer to clean jar. Set lid on top, but don't screw it on. Let the jar sit out at room temperature for 12 to 24 hours (or until thickened). Then refrigerate until ready to use. Keeps for a week or so in the fridge.
A note on timing: If I prepare the buttermilk in the evening, it isn't ready by the time I go to work the next morning. It is ready by the time I get home in the afternoon.
What to do with buttermilk? Buttermilk is fantastic in scones. Buttermilk can also be great in cakes. It's a key ingredient in ranch dressing. Where buttermilk really shines -- sorbet.