Preheat the oven to 300 degrees.

In a mixing bowl, whip together the cream cheese and butter until smooth.

Mix in the sour cream and eggs.

Add in the cornstarch, vanilla, sugar, lemon juice and lemon zest until well combined and smooth.

Pour the mixture into a well greased 9 inch springform pan and bake for 2 hours and 15 minutes.

Let cool for 3 hours, and then chill for a minimum of one hour before serving.