1. Prepare the Oven and Pan, Preheat your oven to 350°F (175°C). Line a 9×13-inch baking pan with foil, then lightly grease the foil. 2. Make the Crust, Place graham crackers in a food processor and blend until fine crumbs form. Combine the crumbs, sugar, and melted butter in a bowl, mixing until fully combined. Press the mixture evenly into the bottom of the prepared pan, using the back of a measuring cup to compact it. Bake for 10-15 minutes, until lightly golden and fragrant. Let cool slightly. 3. Prepare the Filling, In a large bowl, whisk together the pumpkin puree, pumpkin pie spice, cinnamon, and flour. Set aside. In a separate bowl, beat the cream cheese and sugar with a hand or stand mixer until smooth. Add vanilla, sour cream, and salt, and mix until combined. Scrape the bowl’s sides as needed. Add eggs one at a time, mixing just until combined after each addition. Measure 1-½ cups of the cream cheese mixture, then mix it into the reserved pumpkin mixture until smooth. 4. Assemble and Swirl, Alternate spoonfuls of plain cream cheese filling and pumpkin filling on top of the crust. Use a sharp knife to create swirls by dragging through the filling in a figure-eight motion, but avoid reaching down to the crust. 5. Bake and Chill, Bake in the center of the oven for 35-45 minutes. The edges should be set, but the center will have a slight jiggle. Remove and let cool completely on a wire rack, then refrigerate for several hours until fully chilled.