For the caramel sauce: In a medium heavy-bottomed saucepan, combine the sugar, water, and corn syrup. Gently stir to moisten all the sugar, then stop stirring. Set the pan over medium heat and cook undisturbed for 5-10 minutes, until the mixture turns deep amber. Meanwhile, warm the heavy cream in the microwave for about 1 minute. Once the caramel is a rich copper color, remove from heat and carefully pour in the warm cream. Caution: The mixture will bubble up rapidly. Pour slowly and whisk constantly. Whisk until smooth. Stir in the vanilla, salt, and butter. Return to low heat briefly if needed to smooth it out. Let cool slightly, then transfer to a heat-safe jar and refrigerate until ready to assemble. The caramel will thicken as it cools.

For the Graham Cracker Crumbs: In a medium bowl, whisk together the graham cracker crumbs, dark brown sugar, salt, and cinnamon until well combined. Pour in the melted butter and stir with a fork (or your hands) until the mixture looks like wet sand and every bit of crumb is coated - no dry patches left. Set aside while you prepare the cheesecake filling.

For the No-Bake Pumpkin Cheesecake Filling: In a large bowl or the bowl of a stand mixer with the paddle attachment, or with an electric hand mixer, whip the cold heavy whipping cream on medium-high speed until stiff peaks form, about 2-3 minutes. Set aside. In a separate large bowl, beat the softened cream cheese on medium speed until smooth and creamy, about 1-2 minutes. Add the pumpkin puree, powdered sugar, dark brown sugar, vanilla extract, cinnamon, and salt to the cream cheese. Mix on medium speed until fully combined and smooth, scraping down the sides and bottom of the bowl half way through. With the rubber spatula, gently fold the whipped cream into the pumpkin cream cheese mixture in two additions, folding just until no streaks remain - be careful not to overmix, or the filling will lose its light, scoopable texture.

Assembly: Make sure your caramel is completely cool and not warm whatsoever. In your dish of choice, sprinkle half of the graham cracker crumbs evenly across the bottom. Drizzle about a third of the caramel over the crumb layer. Add all of the pumpkin cheesecake filling on top, smoothing it into an even layer with a spatula. Sprinkle the remaining graham cracker crumbs over the filling, then drizzle another third of the caramel on top. Cover and refrigerate for at least 8 hours, up to 24 hours, to allow the cheesecake to set. Serve using a spoon or a large ice cream scoop, with the remaining caramel on the side for drizzling.