Preheat & Prep: Preheat oven to 325°F (165°C). Line a 9×13-inch baking pan with parchment paper, leaving an overhang for easy removal.

Make the Crust: In a bowl, mix graham cracker crumbs, sugar, and melted butter until the texture resembles wet sand. Press mixture firmly and evenly into the bottom of the prepared pan. Bake for 10 minutes, until lightly golden and fragrant. Let cool slightly.

Prepare Cheesecake Base: In a large bowl, beat cream cheese and sugar together until smooth and creamy. Add eggs one at a time, mixing after each addition. Stir in vanilla and flour until just combined (avoid overmixing).

Make Pumpkin Layer: In a separate bowl, mix 1 cup of the cheesecake batter with pumpkin puree, cinnamon, pumpkin pie spice, and sugar until well blended.

Assemble: Pour the plain cheesecake batter over the cooled crust, spreading evenly. Gently spoon the pumpkin mixture on top. Use a butter knife to swirl the two layers together for a marbled effect, or leave layered for a two-tone look.

Bake: Bake for 40–45 minutes, or until the center is set but still slightly jiggly when gently shaken. The edges should look firm and lightly golden.

Cool & Chill: Allow bars to cool completely at room temperature, then refrigerate for at least 4 hours (overnight is best) for a firm texture and clean slices.

Slice & Serve: Use the parchment paper overhang to lift the bars out of the pan. Cut into squares with a sharp knife, wiping between cuts for neat slices. Top with whipped cream, caramel drizzle, or nuts if desired.