Preheat oven to 350 degrees F and line a 9 x 13 baking pan with parchment paper.
Make the Crust:
In a food processor or blender, pulse together 15 cinnamon graham crackers and 1/4 cup granulated sugar until they are a fine crumb.
Slowly add 1/2 cup butter, melted just until combined.
Press the graham cracker mixture into a prepared baking pan in an even layer. Bake for 10 minutes. Allow the crust to cool completely.
Make the Pumpkin Filling:
In a medium mixing bowl, stir together 1 1/2 cups pumpkin purée, 1 tablespoon pumpkin pie spice, and 1 tablespoon all-purpose flour. Set the mixture aside.
Make the Cheesecake Filling:
Add 3 8-ounce packages cream cheese, room temperature and 2 cups granulated sugar to the bowl of the mixer and beat on medium-high speed until light and fluffy.
Reduce the speed to low and add 1/2 cup sour cream, 3 large eggs, room temperature, 2 teaspoons vanilla extract, and 1/4 teaspoon salt.
Scoop 2 cups of the cream cheese mixture and stir it into the pumpkin mixture.
Assembly:
Spoon the pumpkin filling and cheesecake filling all over the crust. Using a butter knife, swirl the two mixtures together to create a swirl pattern.
Bake for 30 to 45 minutes until the edges are set. Allow the bars to cool completely and then place them in the refrigerator for 4 to 6 hours before cutting into individual bars.