Preheat your oven to 350°F (175°C)
Prepare a 9-inch springform pan by wrapping the bottom with parchment paper and greasing the sides.
For the graham cracker crust:
Mix together graham cracker crumbs, brown sugar, and melted butter. Press the mixture evenly into the bottom of the prepared pan. Bake for 10 minutes and let it cool.
For the cheesecake filling:
In a large bowl, beat the cream cheese and sugar until smooth and creamy. Add eggs one at a time, mixing well after each addition. Stir in the vanilla extract and sour cream until well combined.
Pour the cheesecake filling over the cooled crust. Slide the pan onto the lower rack of the oven and bake for 50–60 minutes, or until the center is just set and the edges are slightly firm. Turn off the oven and leave the cheesecake inside for 1 hour before opening. Then cool to room temperature before refrigerating for at least 4 hours or overnight.
While the cheesecake is chilling, prepare the cinnamon spiced apples:
In a bowl, toss the apple slices with sugar, cinnamon, and nutmeg. Set aside.
For the cinnamon streusel topping:
In a bowl, mix together flour, oats, brown sugar, and cinnamon. Stir in melted butter until a crumbly texture forms.
Once the cheesecake is fully chilled, spread the apple mixture evenly over the top. Sprinkle the streusel topping over the apples.
Chill for at least 1 hour before slicing and serving.