Preheat the oven to 325°F (163°C). Wrap the outside of a 9-inch springform pan tightly in two layers of heavy-duty aluminum foil, covering the bottom and going partway up the sides. Lightly grease the inside of the pan with butter or nonstick spray. Heat water in a kettle or pot for the water bath.
In a medium bowl, stir together the graham cracker crumbs, melted butter, granulated sugar, and salt until the mixture resembles wet sand. Press the mixture firmly and evenly into the bottom of the prepared pan. Bake the crust for 10 minutes, then remove it and set aside to cool slightly. Keep the oven on at 325°F.
In the bowl of a stand mixer fitted with the paddle attachment, beat the softened cream cheese on medium speed for 2 to 3 minutes until completely smooth. Scrape down the sides and bottom of the bowl. Add the granulated sugar and brown sugar, and beat on medium speed for another 2 minutes until fully combined.
Add the pumpkin puree, sour cream, pumpkin pie spice, ground cinnamon, vanilla extract, cornstarch, and salt to the cream cheese mixture. Beat on low speed just until combined, scraping down the bowl once halfway through. Avoid overmixing to prevent cracking.
Add the eggs one at a time, beating on low speed after each addition just until the yolk disappears. Stop mixing as soon as the last egg is incorporated. Scrape the bowl one final time and fold gently by hand to ensure nothing is stuck to the bottom.
Pour the filling over the cooled crust and smooth the top with an offset spatula. Place the wrapped springform pan into a large roasting pan. Carefully pour hot water into the roasting pan until it reaches about 1 inch up the sides of the springform pan.
Bake at 325°F for 60 to 70 minutes, until the edges are set and the center still jiggles slightly when the pan is nudged. If using an instant-read thermometer, the center should register around 150°F. Turn off the oven, crack the door open, and let the cheesecake sit inside for 1 hour to cool slowly.
Remove the cheesecake from the water bath and carefully peel off the foil. Run a thin knife around the edge of the pan to loosen the cheesecake. Let cool to room temperature on a wire rack, then cover and refrigerate for at least 6 hours or overnight before releasing the springform sides.
Just before serving, whip the cold heavy cream, powdered sugar, and vanilla extract together until soft peaks form. Spread or pipe the whipped cream over the chilled cheesecake and dust with ground cinnamon. Slice with a warm, clean knife, wiping the blade between cuts.