Preheat your oven to 325°F.

In a medium bowl, combine the graham cracker crumbs, cocoa powder, granulated sugar, and melted butter. Mix until well combined.

Press the mixture firmly into the bottom of a 9-inch springform pan to form the crust. Bake for 10 minutes, then remove from the oven and let it cool.

In a large mixing bowl, beat the softened cream cheese with an electric mixer until smooth. Gradually add the powdered sugar, mixing until well combined.

Add the Nutella and vanilla extract, mixing until smooth.

Add the eggs one at a time, mixing on low speed until just combined after each addition. Be careful not to overmix.

Pour the cheesecake batter over the cooled crust in the springform pan.

Bake for 50-60 minutes, or until the edges are set and the center is slightly jiggly.

Turn off the oven and crack the door, allowing the cheesecake to cool in the oven for 1 hour.

Remove the cheesecake from the oven and let it cool to room temperature. Once cooled, refrigerate for at least 4 hours or overnight for best results.

Before serving, whip the heavy cream until soft peaks form. Spread or pipe the whipped cream on top of the cheesecake. Sprinkle with chopped hazelnuts if desired.