Cooks' note:
Cheesecake keeps, covered and chilled, 2 weeks. Purée farmer cheese (or cottage cheese) with sugar in a food processor until completely smooth before combining with flour and zests. After beating in eggs and vanilla, stir ý cup heavy cream into batter. (Cottage cheese gives a slightly drier result than cream cheese; farmer cheese is slightly drier still.) A cake made from either cheese is best eaten within 2 days.