Bring 3 bottles of cream to a boil and skim off the foam into a separate bowl. To the remaining cream add a ladle of sour cream and return to a boil. As soon as any foam appears, immediately skim it off and add it to that already collected. Add another saucespoon of sour cream to the pan and set it to boil. If any foam appears, remove it. As soon as the cream begins to heat, stir it so that it does not burn, which will happen very easily if you are not careful. When the whey separates, pour everything into a napkin to let the whey drain off. Turn the curds out onto a platter, sprinkle on 1 glass of sugar, and add some kind of flavoring, such as vanilla, cardamom, lemon zest, or mace. Mix thoroughly, pile into a mold, and weight the mold.