• Prep the pan. Preheat oven to 350°F. Lightly grease a 9x9-inch baking pan or line with parchment paper, leaving an overhang for easy lifting.

Make the Crust

• Stir together the graham cracker crumbs, sugar, and cinnamon in a medium bowl. Pour in melted butter and mix until the crumbs are evenly moistened.
  1½ cups graham cracker crumbs, 3 tablespoons granulated sugar, 1 teaspoon ground cinnamon, 6 tablespoons unsalted butter
• Press firmly and evenly into the bottom of the prepared pan. Bake for 8–10 minutes, until fragrant and lightly golden. Remove from oven. Reduce oven temperature to 300°F.

Make Pumpkin Cheesecake Filling

• In a stand mixer or with a hand mixer, beat cream cheese on low speed until smooth, scraping the bowl as needed. Add sugar, flour, and spices; beat for 1–2 minutes until incorporated.
  16 ounces cream cheese, 1¼ cups granulated sugar, 3 tablespoons all-purpose flour, 1½ teaspoons pumpkin spice
• Mix in vanilla and pumpkin until smooth. Add eggs one at a time, mixing well after each addition. Gently fold in sour cream until fully combined.
  ¾ teaspoon pure vanilla extract, ¾ cup pumpkin purée, 3 large eggs, ⅓ cup sour cream
• Bake. Pour filling over the baked crust, smoothing the top. Bake for 40–45 minutes, or until edges are set and the center still has a slight jiggle.
• Cool & chill. Turn off the oven, crack the door, and let the cheesecake cool inside for 1 hour.
• Remove from oven, cover lightly, and refrigerate for at least 4 hours or overnight before slicing into bars.