Preheat an oven to 350°F and set an oven rack to the middle position.

To make the crust, place graham crackers, sugars, cinnamon and sea salt in a food processor, and blitz until finely ground. Drizzle butter over the crumbs, and pulse a few times until mixture resembles wet sand. Press the crumbs into a 9-inch (9.5-inch also workspringform pan in an even layer. Bake for 10 minutes until the crust is golden brown and fragrant. Transfer to a cooling rack, and let cool completely before filling.

Reduce oven heat to 325°Wrap the springform pan in 2 layers of foil, making sure the foil comes all the way up the sides of the pan. Spoon pumpkin puree into a paper towel-lined strainer set over a bowl. Let the puree dry/drain while you prepare the cheesecake batter (at least 5 minutes).

Add cream cheese and sugars to a stand mixer fitted with the paddle attachment. Beat on medium until light and fluffy (4 to 5 minutes). Scrape down the sides, add pumpkin, sour cream, pumpkin pie spice, vanilla and salt, and beat just until combined. Beat in eggs one at a time, scraping down the sides as needed. Remove the bowl from the stand mixer and give the mixture one last stir with a spatula to make sure everything at the bottom is well incorporated.

Pour the cream cheese mixture into the prepared springform pan, smoothing out the top with an offset spatula. Place the springform pan in a roasting pan, then transfer to the oven. Carefully fill the roasting pan with water until it reaches halfway up the side of the springform pan. Make sure you don’t let any of the water splash into the cheesecake. Bake cheesecake until the sides are set and there’s just a slight wobble in the middle (90 - 100 minuteor until the center of the cheesecake registers 150°F.

Turn off the oven, crack the door, and let the cheesecake cool inside the oven for 1 hour. Carefully remove the foil, and let cool for 2 hours on a cooling rack. Cover the cheesecake with plastic wrap and chill completely in the refrigerator (8 hours or overnight).

When ready to serve, wrap the springform pan with a warm towel and let sit for 1 minute. Slowly unclasp the springform pan, and use an offset spatula to help release any stuck bits. Cut cheesecake into 8 even slices and transfer to serving plate. Sprinkle the tops of the slices with 1 tablespoons sugar. Using a kitchen torch, cook the sugar until deeply golden and blackened in spots. Sprinkle the tops of the slices with remaining sugar and repeat the torching process. The crème brûlée topping will soften as it sits, so it’s best to serve immediately after torching.