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

2. Combine graham cracker crumbs, melted butter, brown sugar, and cinnamon and press firmly into the bottom of the pan.

3. Bake the crust for 8–10 minutes until lightly golden and set aside to cool.

4. In a saucepan over medium heat, melt butter and cook diced apples with cinnamon, nutmeg, brown sugar, and lemon juice until apples are tender and syrup thickens.

5. Allow the spiced apple mixture to cool to room temperature before spreading it over the cooled crust.

6. Beat softened cream cheese until smooth, then add sugar and vanilla and mix until combined.

7. Add eggs one at a time, mixing just until incorporated, then blend in sour cream until the batter is glossy.

8. Pour the cheesecake filling over the apple layer and smooth the top with a spatula.

9. Place the springform pan on a baking sheet and bake for 50–55 minutes until the center is set but still slightly wobbly.

10. Turn off the oven, crack the door open, and let the cheesecake rest inside for 1 hour to cool gradually.

11. Run a knife around the edge of the pan, let the cheesecake cool completely, then refrigerate for at least 4 hours or overnight.

12. Melt the chocolate over a double boiler or in short microwave bursts and let it cool slightly.

13. Whip heavy cream with sugar and espresso until soft peaks form, then fold gently into the cooled chocolate to create the mousse.

14. Spread the chocolate mousse evenly over the chilled cheesecake and refrigerate for at least 1 hour to set.

15. Release and remove the springform pan, transfer the cheesecake to a serving plate, and garnish as desired with caramel drizzle, apple slices, or chocolate shavings.