Kwark is more about patience than skill. Make sure you avoid any buttermilk that contains any kind of gums, cornstarches or any other ingredient that is not natural to cows: it suspends the whey in the liquid and does not allow for proper drainage.
6 cups of whole milk
2 cups buttermilk (avoid buttermilks with gums, cornstarch etc)
Pour both milks in a heavy pan and slowly bring up to 100F. Cover the pan and let it sit at room temperature overnight. The next day, the whey should have separated from the milk solids. Pour everything into a tea towel, knot the four ends together and suspend the package from the kitchen cabinet’s door knob. Place a bowl underneath to catch the whey. Suspend for a good three hours or until the whey has stopped draining.
Scrape the kwark out of the towel and fluff up with a fork. If it’s too dry, add a tablespoon or two of milk. If it’s still too wet, continue to drain for a little bit longer. You are looking for a thicker yoghurt consistency.
Makes two cups of kwark.