Preheat your oven to 325°F (160°C) and grease a 9-inch springform pan.

In a large mixing bowl, beat the softened cream cheese and granulated sugar together using an electric mixer until smooth and creamy, about 2-3 minutes.

Add in the eggs one at a time, beating well after each addition. Mix in sour cream and vanilla extract until fully combined.

In a separate bowl, toss sliced apples with brown sugar, a teaspoon of cinnamon, and a pinch of salt. Let sit for about 15 minutes.

In another bowl, combine oats, flour, brown sugar, and cold, cubed butter. Blend until it resembles coarse crumbs.

Pour half of the cheesecake filling into the bottom of the prepared springform pan. Layer the spiced apples over the cheesecake layer.

Top with the remaining cheesecake filling and sprinkle the crumble topping generously over the apples.

Bake for approximately 45-50 minutes until the edges are set and the center jiggles slightly.

Let cool at room temperature for about 30 minutes, then refrigerate for at least 4 hours, preferably overnight.

Before serving, remove from springform pan and slice with a warm, wet knife. Serve with whipped cream or vanilla ice cream if desired.