Preheat the oven to 300F/150C.
Using an electric mixer, beat together the cream cheese, sugar, vanilla extract, lemon zest, lemon juice, cornstarch, and salt until smooth and creamy.
Add the ricotta and continue to mix until just combined.
Add the eggs one at a time, mixing between each addition until combined.
Add the cheesecake to the muffin pan, filling almost to the top of each well. Add a small spoonful of raspberry swirl sauce to each well. Use a toothpick or other utensil to draw swirls on top of the cheesecake, taking care not to overmix (contrast is desired).
Bake at 300F/150C for 20-22 minutes. The center should still jiggle when the pan is shaken, but the edges should be set.
Allow the cheesecake to cool to room temperature, then refrigerate for 2-4 hours.