Preheat your oven to 350°F (175°C). Line a 9x13-inch baking pan with foil and lightly grease the foil for easy removal and cleanup. I always recommend using a metal pan for best results, though a glass pan will work; just note that it may require a few extra minutes of baking time.

Place the graham crackers in the bowl of a food processor and process until they form fine crumbs—this should yield just over 2 cups. In a separate bowl, combine the graham cracker crumbs with the white sugar and melted butter, stirring until everything is evenly moistened. Press this mixture firmly and evenly into the bottom of the prepared pan using the back of a measuring cup to ensure a compact, even layer. Bake the crust for 10-15 minutes, until it just begins to turn golden brown and smells toasty. Set the pan on a wire rack to cool slightly while you prepare the filling.

In a large bowl, whisk together the pumpkin puree, pumpkin pie seasoning, ground cinnamon, and flour until smooth and well combined. Set this pumpkin mixture aside; it will be combined with a portion of the cream cheese filling in a later step. I sometimes like to add a pinch more cinnamon here for extra warmth and spice.

In a large bowl, use a hand mixer or stand mixer with the paddle attachment to beat the softened cream cheese and granulated sugar together until completely smooth and creamy. Add the vanilla extract, full fat sour cream, and salt, and continue beating until fully combined. Beat in the room temperature eggs one at a time, mixing just until each egg is fully incorporated to avoid overbeating. Make sure to scrape the sides of the bowl as needed.

Measure out 1-1/2 cups of the cream cheese mixture from Step 4 and gently fold it into the pumpkin mixture from Step 3 until fully combined. Dollop alternating scoops of plain cream cheese filling (from Step 4) and pumpkin-cream cheese filling (from this step) all over the surface of the cooled crust. Use a sharp knife to swirl the two mixtures together in a decorative pattern—I like to make figure eights for a beautiful marbled effect. Be careful not to drag the knife down so far that it disturbs the crust underneath.

Bake the assembled bars in the center of the preheated oven for 35-45 minutes. The edges should look set while the center retains a very slight jiggle; do not overbake. Once done, place the pan on a wire rack and allow it to cool completely. Then, transfer the bars to the refrigerator and chill for several hours until firm—this helps the flavors meld and ensures clean slices. For the best presentation, I like to refrigerate them overnight before serving.