Start with 2 quarts buttermilk, as fresh as possible. Pour into
oven-safe container with lid. Let sit in oven overnight (at least
8 hours), at 150 degrees.
Line a colander with a clean cloth, pour quark in colander, let
drain in fridge. If it drains too slowly, can fold cloth over the
top, and set a sealed tupperware bowl filled with water on top.
To use, can mix in a little milk until smooth. Wonderful with a
little fructose, and pureed fruit.