Preheat the oven to 350 degrees F (175 degrees C). Lightly grease a 9-inch springform pan.
Mix cream cheese and ricotta cheese together in a mixing bowl until well combined. Add eggs, sugar, butter, flour, cornstarch, lemon juice, and vanilla; mix to combine. Stir in sour cream and pour into the prepared pan.
Bake in the preheated oven for 1 hour. Turn the oven off; allow cheesecake to cool in the oven with the door closed for 1 hour more to prevent cracking. Cool cheesecake completely in the refrigerator before serving.