Prepare Raspberry Sauce by combining raspberries, sugar, and lemon juice in a medium saucepan. Heat over medium heat, stirring until it thickens. Stir in cornstarch slurry and cool.

Make Crust by mixing graham cracker crumbs, melted butter, brown sugar, and salt. Press mixture into the bottom of an 8x8-inch baking pan and pre-bake at 350°F for 10 minutes.

Cheesecake Filling: Beat cream cheese until smooth, then mix in sour cream, sugar, cornstarch, vanilla, and salt. Add eggs one at a time, mixing just until blended.

Assemble by pouring cheesecake filling over the cooled crust. Spoon raspberry sauce on top and swirl gently to create a marbled effect.

Bake at 325°F for about 30 minutes until edges are set but the center is slightly jiggly.

Cool for at least 1 hour, then refrigerate for 4 hours before slicing into squares to serve.