Prepare the crust: Preheat the oven to 325°F (163°C). Grease and line the bottom of a 9-inch springform pan with parchment paper. Combine graham cracker crumbs, sugar, and melted butter, then press into the pan. Bake for 8-10 minutes, then cool.

1. Prepare the filling: Beat softened cream cheese, sugar, and vanilla extract until smooth. Add Nutella and mix until fully combined. Add eggs one at a time, mixing well. Stir in sour cream, heavy cream, flour, and salt until smooth.
2. Bake the cheesecake: Pour filling into the cooled crust and smooth the top. Bake for 55-65 minutes, or until the edges are set and the center is slightly jiggly. Turn off the oven, cool for 1 hour, then refrigerate for at least 4 hours, or overnight.
3. Top and serve: Top with whipped cream, chopped hazelnuts, Nutella drizzle, and shaved chocolate or cocoa powder. Serve chilled.