Prepare the pan. Place a rack in the center of the oven, then preheat to 350°F (177°C). Butter the bottom and sides of the springform pan, then wrap in a double layer of heavy duty aluminum foil.
Make the graham cracker crust. Combine 2 cups (240g) graham cracker crumbs, 5 Tbsp (63g) sugar, and a pinch of Kosher salt in a mixing bowl. Add 8 Tbsp (113g) melted butter, then stir until evenly moistened. Pour the mixture into the greased pan, then press into an even layer along the bottom, reaching about halfway up the sides. Bake for 10 minutes. Remove and let cool slightly while you make the filling. Reduce the oven temperature to 325°F (163° C).
Boil water. Heat a kettle with water to be used for the water bath.
Make the cheesecake filling. Beat 2 lb cream cheese, ⅔ cup (147g) brown sugar, ⅔ cup (134g) granulated sugar, 2 tsp vanilla extract, ½ tsp ground cinnamon (reserve the rest), and a pinch of Kosher salt in the bowl of a stand mixer until smooth and creamy, about 4 minutes. Scrape down the sides, then add 4 eggs, one at a time, beating for about 1 minute after each addition. and beat on medium-low until fully incorporated and the mixture is fluffy. Reduce the speed of the mixer to low, then add ⅔ cup (160g) heavy cream, ⅔ cup (163g) sour cream, and 1 Tbsp maple syrup or bourbon. Once fully mixed, turn off the mixer, then use a spatula to scrape down the sides and ensure that everything from the bottom is mixed in.
Make the pumpkin batter. Transfer 1 cup of the cheesecake batter to a separate mixing bowl. To this, add 1 cup of pumpkin purée, 1 tsp ground cinnamon, ½ tsp ground ginger, ½ tsp ground nutmeg, and a pinch of allspice, then whisk well.
Bake the cheesecake. Pour the plain cheesecake batter on top of the cooled graham cracker crust. Dollop the pumpkin batter on top in 4 or 5 spots. Use a butter knife to swirl into a marble pattern, just near the top of the cheesecake. Place the cheesecake in a large roasting pan, then transfer to the preheated oven. Pour enough boiling water to come halfway up the side of the springform pan. Bake for 1 hour 45 minutes, or until the edges of cheesecake turn golden brown and pull away from the sides. The middle of the cheesecake will be a little jiggly.
Cool in the oven. Turn the oven off, then crack the door slightly. Let the cheesecake cool for an hour in the oven, then remove from the oven. Carefully remove the foil, then continue to cool at room temperature until fully cool. Cover tightly with plastic wrap or foil, then refrigerate for 4 hours or overnight.
Slice, then serve. Use a sharp knife to loosen the sides of the cheesecake from the pan, then gently open and remove the springform pan. If using whipped cream, I like to pipe that in a decorative way around the outer edges of the cheesecake. See tip below for slicing cheesecake.