Prepare the Pan and Crust:

1. Preheat and prep: Preheat your oven to 325°F (163°C). Line a 9×13-inch baking pan with aluminum foil or parchment paper, leaving overhang on the sides for easy removal later. Lightly spray with non-stick cooking spray.

2. Make the crust: In a medium bowl, combine graham cracker crumbs, melted butter, sugar, and salt. Mix with a fork until the mixture resembles wet sand and holds together when pressed.

3. Press the crust: Pour the crumb mixture into your prepared pan. Press firmly and evenly into the bottom using the bottom of a measuring cup or your hands. Make sure it’s compact and reaches all corners.

4. Pre-bake: Bake the crust for 10 minutes. Remove from oven and set aside to cool slightly while you prepare the filling.

Make the Raspberry Swirl:

5. Cook raspberries: In a medium saucepan over medium heat, combine raspberries, sugar, and 2 tablespoons water. Cook, stirring occasionally and mashing the berries with a spoon, until the mixture breaks down and becomes juicy, about 5 minutes.

6. Thicken: Mix cornstarch with 1 tablespoon water to create a slurry. Add to the raspberry mixture along with lemon juice. Stir constantly and cook for 1-2 minutes until the mixture thickens noticeably.

7. Strain (optional): For a smoother sauce without seeds, press the mixture through a fine-mesh strainer. For more texture, leave it as is. Set aside to cool slightly.

Make the Cheesecake Filling:

8. Beat cream cheese: In a large bowl using an electric mixer, beat the softened cream cheese on medium speed for 2-3 minutes until completely smooth, creamy, and fluffy with no lumps. Scrape down the sides of the bowl frequently.

9. Add sugar: Add the sugar and beat for another 2 minutes until well combined and fluffy.

10. Add sour cream: Mix in the sour cream and vanilla extract, beating until smooth and incorporated.

11. Add flour: Add the flour and mix just until combined.

12. Add eggs: Add eggs one at a time, beating on low speed after each addition just until incorporated. Don’t overmix—too much air creates cracks. Scrape down the bowl between additions.

Assemble and Bake:

13. Pour filling: Pour the cheesecake batter over the pre-baked crust, spreading it evenly with a spatula. Gently tap the pan on the counter a few times to release air bubbles.

14. Add raspberry swirl: Drop spoonfuls of the raspberry mixture over the top of the cheesecake filling, distributing it somewhat evenly across the surface.

15. Create swirl: Using a knife, toothpick, or skewer, gently swirl the raspberry through the cheesecake in figure-eight or S-shaped patterns. Don’t over-swirl or the colors will muddy—a few swirls create beautiful marbling.

16. Bake: Bake at 325°F for 38-42 minutes. The cheesecake is done when the edges are set but the center still has a slight wobble when you gently shake the pan (about 2-3 inches in the center). It will firm up as it cools.

Cool and Chill:

17. Cool gradually: Turn off the oven and crack the door open. Let the cheesecake bars cool in the oven for 30 minutes. This gradual cooling helps prevent cracks.

18. Room temperature cool: Remove from oven and cool completely to room temperature on a wire rack, about 1-2 hours.

19. Refrigerate: Cover the pan with plastic wrap and refrigerate for at least 4 hours, but preferably overnight. The bars must be completely cold and firm before cutting.

20. Cut and serve: Use the foil or parchment overhang to lift the entire cheesecake out of the pan. Place on a cutting board. Use a large, sharp knife (wiped clean between cuts) to slice into 24 bars. Serve chilled and enjoy!