Preheat your oven to 175°C (350°F).

In a mixing bowl, combine the graham cracker crumbs, melted unsalted butter, and granulated sugar. Press this mixture into the bottom of a 23-centimeter springform pan.

In a skillet, melt unsalted butter and sauté sliced apples, brown sugar, ground cinnamon, and nutmeg for 5 to 7 minutes. Let cool.

Beat together softened cream cheese, granulated sugar, and vanilla extract until smooth. Add eggs one at a time, mixing just until incorporated.

Pour half of the cheesecake mixture over the crust, then add half of the cooled apple filling. Repeat with remaining cheesecake mixture and apples.

Combine all-purpose flour, oats, brown sugar, and cinnamon. Cut in cold butter until resembling coarse crumbs. Sprinkle over layers.

Bake for 50 to 60 minutes until the center is set but slightly jiggly. Let cool before chilling.

Refrigerate for at least 4 hours or overnight. Slice and serve.