Preheat your oven to 350°F (175°C).
Prepare the crust by combining graham cracker crumbs, melted butter, and granulated sugar.
Press the mixture firmly into the base of a springform pan.
Bake the crust for 10 minutes, then set aside to cool.
Prepare the apple filling by mixing sliced apples with cinnamon and brown sugar.
Spread the apple mixture evenly over the cooled crust.
In a bowl, blend the cream cheese, powdered sugar, eggs, and vanilla until smooth.
Pour the cream cheese mixture over the apple layer.
Prepare the crumble topping by mixing oats, flour, brown sugar, and salt.
Melt butter and mix it into the crumble ingredients until crumbly.
Sprinkle the crumble topping over the cheesecake filling.
Bake the cheesecake for 50-60 minutes until the edges are set but the center is slightly jiggly.
Turn off the oven and let the cheesecake cool inside for an hour.
Remove from the oven and chill in the refrigerator for at least 4 hours or overnight.
Slice and serve the cooled cheesecake.