Austrian Cheesecake

Preheat the oven to 300 degrees F. Press the cheese through a sieve. In a large mixing bowl, beat together the cheese and sugar until light. Add the egg yolks, one at a time, beating well after each addition, then add the milk, lemon rind, and vanilla. Stir in the flour and blend until smooth. In another large mixing bowl, beat the egg whites until they form soft peaks, then gradually add the confectioners' sugar beating until they form stiff peaks. Fold the whites into the cheese mixture. Gently stir in the rai