In stand mixer or large bowl, beat the cream cheese and butter until smooth. Beat in the hot milk. Beat in the egg yolks and then beat in the lemon zest, lemon juice, and vanilla extract.
Sift or whisk together the flour and cornstarch. Stir the flour mixture into the cream cheese mixture.
Fold the whipped egg whites into the batter. Pour the batter into the prepared cake pan (if your cake pan isn't tall enough, you may have extra batter. Don't fill the cake pan more than 85% up to give room for the cake to rise without spilling out of the pan).
In a water bath filled with gently boiling water *see head note, bake the cheesecake for 1 hour 10 minutes or until set. Allow to cool to room temperature and serve with the berry sauce (directions below).