Prepare the Crust
Combine the graham cracker crumbs, melted butter, sugar, and cinnamon in a medium bowl until the mixture resembles wet sand. The perfect consistency should hold its shape when pressed between your fingers—if it's too crumbly, add an additional tablespoon of melted butter.Press the mixture firmly into the bottom of a 9-inch springform pan, using the flat bottom of a measuring cup to create an even, compact layer. For extra stability, press some of the mixture about 1/2 inch up the sides of the pan.
Chill the crust in the freezer for 15 minutes while preparing the filling.
Create the Cheesecake Filling
In a large bowl, beat the softened cream cheese until completely smooth and free of lumps—about 2 minutes with an electric mixer.Add the powdered sugar gradually, beating after each addition until well combined. Mix in the vanilla extract and sour cream until smooth and creamy.
In a separate bowl, whip the heavy cream until stiff peaks form. Gently fold the whipped cream into the cream cheese mixture using a rubber spatula. Be careful not to overmix—stop when the mixture is just combined to maintain maximum fluffiness.
Make the Apple Topping
In a medium saucepan, melt the butter over medium heat. Add the diced apples, brown sugar, lemon juice, and spices. Cook for about 8-10 minutes, stirring occasionally, until the apples are tender but still hold their shape.Add the cornstarch-water mixture and cook for an additional 1-2 minutes until the sauce thickens. Remove from heat and allow to cool completely.
Assemble the Cheesecake
Spread the cheesecake filling evenly over the prepared crust. Smooth the top with a spatula or the back of a spoon.Refrigerate the cheesecake for at least 3 hours or overnight to set properly.
Once the cheesecake has set and the apple topping has cooled completely, spread the apple mixture evenly over the top of the cheesecake.
Optionally, reserve about 1/4 cup of the apple topping to add just before serving for an extra fresh texture contrast.