Put cheese through a sieve twice. Cream butter until white (preferably with an electric mixer). Cut up vanilla very fine and mix with sugar. Beat egg yolks well and add sugar, beating until almost white. Combine egg yolk mixture and butter and beat until smooth and well blended. Add butter-egg mixture to the cheese and beat with a wooden spoon. Whip cream and add it gently to the mixture, turning from bottom to top slowly to fold in the cream. Wrap paskha in cheesecloth (damp gauze may be used) and place it in a paskha from or a clean terra cotta flower pot with a hole in the bottom. Close cheesecloth or gauze over the top of the paskha and place either a wooden square of paskha form or a weight on top (a small, heavy casserole or two or three cans will do). Leave in the refrigerator on a plate for one day so that the liquid can drain off the paskha. Before serving, remove the paskha from the refrigerator, remove the weight, unwrap the cheesecloth ends, place a large round platter over the top, and quickly invert the paskha onto the platter. Remove cheesecloth.