• Preheat oven to 350°F / 177°C. Line an 8x8 baking pan with two overlapping pieces of parchment paper, leaving enough overhang on each side to lift the bars out later. Set aside.

Raspberry Swirl

• Whisk the granulated sugar and cornstarch together in a medium saucepan to remove any lumps.
• Add the raspberries and lemon juice, stirring to coat. Cook over medium heat, stirring frequently, until the raspberries release their juice and the mixture thickens, about 5 minutes. Remove from heat and strain through a fine-mesh sieve, discarding the seeds. Let the sauce cool completely.

Crust

• Pulse the cookie crumbs and brown sugar in a food processor until finely combined. Add the melted butter and process until the mixture resembles wet sand. Press firmly into the bottom of the prepared pan using the flat bottom of a measuring cup.
• Bake the crust for 10 minutes, until lightly golden and fragrant. Remove from the oven and reduce the temperature to 325°F.

Cheesecake Filling

• While the crust bakes, beat the cream cheese, sugar, lemon juice, and vanilla extract with an electric mixer until smooth, about 2 minutes. Add the sour cream and beat until creamy.
• Add the eggs one at a time, beating on low speed just until incorporated. Do not overmix. Pour the filling evenly over the crust.
• Drop the cooled raspberry sauce by the teaspoon over the filling. Use a knife or skewer to gently swirl it in, creating a marbled pattern.
• Bake for 35–40 minutes, until the edges are set and slightly puffed but the center still has a slight jiggle. Cool completely at room temperature, then refrigerate for at least 4 hours or overnight.
• Lift the cheesecake out using the parchment overhang. Cut into 9 bars with a clean, sharp knife, wiping the blade between cuts. Serve chilled; store in an airtight container in the fridge for up to 4 days.