Preparing the Crust:
- Preheat the Oven: Begin by preheating your oven to 350°F (175°C). Then, line a 9×13 baking pan with foil, ensuring that the foil hangs over the edges for easy removal later. Lightly grease the foil with cooking spray to prevent sticking.
- Make the Graham Cracker Crust: In a food processor, pulse the graham crackers into fine crumbs (you should have just over 2 cups). In a separate bowl, combine the graham cracker crumbs, sugar, and melted butter. Stir the mixture until everything is well combined.
- Press the Crust: Firmly press the crust mixture into the bottom of the prepared pan, ensuring an even layer. You can use the back of a measuring cup to help press the crumbs down evenly.
- Bake the Crust: Place the crust in the preheated oven and bake for 10-15 minutes, or until it begins to turn golden brown and fragrant. Once done, remove the pan from the oven and place it on a wire rack to cool slightly.
Preparing the Filling:
- Mix the Pumpkin and Spices: In a large bowl, whisk together the pumpkin puree, pumpkin pie spice, ground cinnamon, and flour. Set this mixture aside.
- Cream the Cream Cheese and Sugar: In the bowl of a stand mixer (or using a hand mixer), beat the cream cheese and sugar together on medium speed until smooth and creamy. Be sure to scrape down the sides of the bowl as needed to ensure everything is well combined.
- Add Vanilla, Sour Cream, and Salt: Once the cream cheese and sugar mixture is smooth, add the vanilla extract, sour cream, and salt. Mix until everything is well incorporated.
- Add the Eggs: Add the eggs one at a time, mixing well after each addition. Make sure to scrape the sides of the bowl to fully incorporate the eggs. Stop mixing once the eggs are fully blended.
- Combine with Pumpkin Mixture: Measure out 1-½ cups of the cream cheese mixture and stir it into the reserved pumpkin mixture until fully combined. This will give the bars the beautiful pumpkin swirl when baked.
Assembling and Baking the Bars:
- Assemble the Layers: Start by alternately spooning dollops of the cream cheese filling and the pumpkin mixture over the cooled graham cracker crust. Spread the fillings out in an even layer, ensuring they’re well distributed.
- Swirl the Mixtures: Using a sharp knife or a toothpick, gently swirl the two mixtures together to create a marbled effect. Be careful not to drag the knife all the way to the crust.
- Bake the Bars: Place the pan in the oven and bake for 35-45 minutes, or until the center is just slightly jiggly, and the edges are set. Keep an eye on them to prevent overbaking.
- Cool and Chill: Once the bars are baked, remove them from the oven and set them on a wire rack to cool completely. After they have cooled to room temperature, transfer the pan to the refrigerator and chill for at least 8 hours (overnight is ideal).