Preheat the oven to 325°F. Lightly spray an 8x8-inch light-colored metal baking pan with nonstick cooking spray, then line it with parchment paper, leaving a little overhang on the sides for easy lifting.
In a mixing bowl, stir together 1 ¼ cups graham cracker crumbs, 5 tablespoons melted unsalted butter, 1 tablespoon granulated sugar, and a pinch of kosher salt until evenly moistened.
Press the graham cracker mixture firmly into the prepared pan, then bake on the center rack for 8 minutes. Remove the crust from the oven and set it aside.
Add 12 ounces softened cream cheese and ½ cup granulated sugar to a large mixing bowl, then beat on medium speed for 1-2 minutes, until smooth and creamy.
Add 3 tablespoons room temperature sour cream and 1 ½ teaspoons pure vanilla extract, then beat just until combined.
Add 1 room temperature large egg and 1 room temperature large egg yolk, mixing on low speed for 10-15 seconds after each addition, just until the yellow disappears. Stop the mixer and finish gently with a rubber spatula. Do not overmix.
Scoop ⅓ cup of the plain cheesecake batter into a medium bowl. Add ⅓ cup pure pumpkin puree, 1 ½ tablespoons packed light brown sugar, 1 ½ teaspoons all-purpose flour, ¾ teaspoon pumpkin pie spice, and a pinch of kosher salt, then stir until smooth.
Spread about two-thirds of the plain cheesecake batter over the baked crust. Dollop the pumpkin mixture over the top, then dollop the remaining plain cheesecake batter between the pumpkin dollops.
Use a butter knife to gently swirl the batters together, being careful not to drag the knife too deeply into the crust. Stop once the batter looks marbled.
Bake on the center rack for 38-43 minutes, until the edges look set and only the center 2 inches has a soft wobble when the pan is gently nudged. The center should not look wet, loose, or sloshy.
Turn the oven off, crack the oven door, and let the bars sit in the oven for 10 minutes. Transfer the pan to the counter and cool uncovered for 1 hour.
Cover the pan without touching the surface of the bars, then refrigerate for at least 4 hours, or until fully chilled and firm.
Lift the chilled bars out of the pan using the parchment paper, then slice into 9 bars with a sharp knife. Wipe the knife between cuts for cleaner slices.
Top with whipped cream, if desired, then serve chilled and ENJOY!
Notes
A light-colored metal baking pan works best for this recipe. Glass, ceramic, or porcelain dishes can cause the bars to bake more slowly and may increase the risk of cracking.
Use full-fat block cream cheese for the smoothest, richest texture. Room temperature cream cheese, sour cream, and eggs will also help the batter mix smoothly without lumps.
Do not overmix after adding the egg and egg yolk. Too much air in the batter can make cheesecake puff up and crack as it bakes.
The bars are done when the edges look set, but the center 2 inches still has a gentle jiggle. They will continue to firm up as they cool and chill.
Nutritional information is approximate and was calculated using a recipe nutrition label generator and will vary based on cooking methods and brands of ingredients used. Does not include optional toppings.★ Did you make this recipe? Don't forget to give it a star rating below!