In a large bowl combine the crumbs and melted butter. Spread ¾ of the crumbs and halfway up the sides of a greased or sprayed 8-9 inch/20-22 cm springform pan or line the pan with parchment or plastic wrap, chill while making the filling.
In a large bowl beat the mascarpone, cream and sifted powdered sugar until thick, fold in the Nutella.
Spread the filling evenly in the chilled crumb base, sprinkle the top with the remaining crumb mixture and top with the chopped hazelnuts. Cover and chill for 2-3 hours, in the last 20 minutes place in the freezer. Drizzle with Nutella or melted chocolate and serve. Enjoy!
Notes
To soften the Nutella immerse the jar in a small pot of water, stir until smooth.This cake is a great make-ahead dessert. You can prepare it up to 2 days in advance and keep it covered in the fridge until ready to serve.
To store leftovers
Cover the cake tightly with plastic wrap or transfer slices to an airtight container. Store in the fridge for up to 4 days. The texture stays light and creamy.