1. Prepare the graham cracker crust by mixing crushed graham crackers with melted butter and pressing it into a 9-inch springform pan.
2. Make the cheesecake filling by beating cream cheese, sugar, eggs, and vanilla until smooth.
3. Pour the cheesecake filling over the prepared crust and spread evenly.
4. Peel and chop Granny Smith or tart apples, then mix them with cinnamon and sugar.
5. Evenly distribute the apple mixture over the cheesecake layer.
6. Prepare the streusel topping by combining oats, flour, brown sugar, cinnamon, and melted butter.
7. Sprinkle the streusel topping evenly over the apple layer.
8. Preheat the oven to the recommended temperature and place the cheesecake in the oven.
9. Bake for the specified time or until the center is set and the streusel is golden brown.
10. Remove the cheesecake from the oven and let it cool at room temperature.
11. Transfer the cheesecake to the refrigerator and chill for several hours or overnight to set.
12. Before serving, drizzle caramel sauce over the top of the cheesecake.
13. Slice and serve chilled for best texture and flavor.
14. Store leftovers in the refrigerator or freeze for up to 6 months.