1. Preheat oven to 350°F (175°C) and line a 9×13-inch pan with parchment paper.

2. Combine graham cracker crumbs, brown sugar, cinnamon, and melted butter; press into pan and bake 8–10 minutes.

3. Reduce oven temperature to 325°F (160°C).

4. Beat 16 ounces cream cheese until smooth, then add granulated sugar and mix on low speed.

5. Add pumpkin puree, eggs one at a time, sour cream, vanilla, and pumpkin pie spice until just combined.

6. In a separate bowl, beat 8 ounces cream cheese with sugar, egg yolk, and vanilla for the swirl.

7. Pour pumpkin mixture over cooled crust and smooth the top.

8. Drop spoonfuls of plain cheesecake mixture over pumpkin layer and swirl gently with a skewer.

9. Bake for 40–45 minutes until edges are set and center slightly jiggles.

10. Cool on a wire rack for 1 hour, then refrigerate 3–4 hours or overnight.

11. Lift bars using parchment and cut into 12 squares, wiping knife between cuts.