Prepare the Crust : Preheat your oven to 325°F (160°C). Line a 9x13-inch baking pan with parchment paper, leaving an overhang for easy removal. In a medium bowl, mix graham cracker crumbs, light brown sugar, and melted butter until combined. Press this mixture firmly into the prepared pan to form an even crust. Bake for 10 minutes and let it cool.

Make the Cheesecake Layer : In a large mixing bowl, beat the cream cheese until smooth. Add granulated sugar, sour cream, eggs, vanilla extract, and salt. Beat until creamy and well-blended. Pour the cheesecake mixture over the cooled crust, spreading it evenly.

Create the Cinnamon Swirl : In a small bowl, mix dark brown sugar, cinnamon, and flour. Sprinkle this mixture evenly over the cheesecake layer. Using a knife or skewer, gently swirl the cinnamon mixture into the cheesecake layer to create a marbled effect.

Bake and Cool : Bake for 40 minutes or until the edges are set and the center jiggles slightly. Remove from the oven and allow the bars to cool to room temperature. Refrigerate for at least 2 hours, or until fully chilled.

Serve and Enjoy : Lift the bars out of the pan using the parchment overhang and cut into squares. Serve cold and enjoy the rich flavors of cinnamon and cheesecake!