2 C half and half
Pour the buttermilk into a bowl. "Splash" in 2 C half and half. DO NOT STIR IT! SIMPLY POUR IT IN. Cover with a lid and leave out for 12 -48 hours to achieve desired sourness and thickness. Once it's how you like it, place it in the refrigerator to stop the cultures from growing. It will keep for a week.
I found this recipe here.
