Make the filling: Lower the oven temperature to 300ºF. In a clean food processor, combine the cream cheese, sugar, and salt and process until smooth. Add the egg, lemon juice, and vanilla and process until smooth, scraping down the bowl and blade as needed. Spread the cheesecake batter over the baked crust and bake until the cheesecake is slightly puffed on top and wobbles very slightly when you give it a wiggle, 30 to 40 minutes. Let cool slightly.