Preheat the oven to 350°F (175°C). Line a 9×13-inch baking pan with parchment paper, leaving an overhang on the sides for easy removal. Lightly spray the parchment paper with nonstick cooking spray to ensure a smooth release.

In a medium-sized mixing bowl, combine the graham cracker crumbs, granulated sugar, ground cinnamon, and melted butter. Stir thoroughly until the mixture resembles wet sand. Firmly press this mixture into the bottom of the prepared baking pan, ensuring an even layer.

Bake the crust for approximately 10 minutes, then remove it from the oven and allow it to cool completely. Reduce the oven temperature to 325°F (160°C).

In a separate medium-sized bowl, whisk together the canned pumpkin puree, pumpkin pie spice, cornstarch, and salt until fully incorporated. Set aside until ready to use.

In a large mixing bowl, beat the softened cream cheese and granulated sugar using an electric mixer set to medium speed. Continue mixing for approximately 2 minutes, or until the mixture is smooth and creamy.

Gradually add the sour cream, vanilla extract, and salt, mixing at low speed until just combined. Incorporate the eggs, adding them one at a time and mixing only until each egg is fully blended. Avoid overmixing, as this may result in undesirable cracks in the cheesecake.

Measure approximately one cup of the prepared cheesecake filling and gently fold it into the pumpkin mixture.

Pour the remaining plain cheesecake filling over the cooled crust, spreading it evenly. Spoon dollops of the pumpkin mixture over the cheesecake layer. Using a knife or toothpick, gently swirl the two mixtures to create a marbled appearance.

Place the pan in the preheated oven and bake for 40-45 minutes, or until the edges are set and the center exhibits a slight jiggle when gently shaken.

Turn off the oven and leave the oven door slightly ajar, allowing the cheesecake to cool gradually for 30-60 minutes. This slow cooling process minimizes the risk of cracks forming.

Remove the pan from the oven and place it on a wire rack to cool completely at room temperature. Once cooled, refrigerate the cheesecake for a minimum of 4 hours, or preferably overnight, to allow it to set completely.

Using the parchment paper overhang, carefully lift the cheesecake from the pan. Slice into squares or bars, wiping the knife clean between cuts to ensure neat edges.

Serve chilled, optionally garnished with whipped cream or a drizzle of caramel sauce.