Combine graham cracker crumbs, melted butter, sugar, and cinnamon in a medium bowl, mixing until the texture resembles wet sand.
Press the mixture firmly into the bottom of a 9-inch springform pan using the flat bottom of a measuring cup. Refrigerate while preparing the filling.
In a large bowl, beat the softened cream cheese until smooth and fluffy, about 2 minutes. Add the sugar and vanilla, continuing to beat until well incorporated.
Dissolve the gelatin in hot water, stirring until completely clear. Allow it to cool slightly (but not set) before slowly streaming it into your cream cheese mixture while beating on low speed.
In a separate bowl, whip the cold heavy cream until stiff peaks form. Gently fold the whipped cream into the cream cheese mixture using a spatula, maintaining as much air as possible.
Pour the filling over your prepared crust, using an offset spatula to create a smooth, level surface. Tap the pan gently on your counter a few times to release any air bubbles. Refrigerate for at least 2 hours before adding the topping.
For the apple topping: In a medium saucepan over medium heat, melt the butter. Add the diced apples, brown sugar, cinnamon, nutmeg, and salt. Cook for 5-7 minutes until the apples are tender but still hold their shape.
Add the cornstarch slurry to the apple mixture, stirring constantly until the sauce thickens, about 1-2 minutes. Remove from heat and allow to cool completely.
Once the apple topping has cooled, spoon it evenly over your set cheesecake. Return to the refrigerator for at least 2 more hours, preferably overnight, to allow flavors to meld.