Preheat oven to 350°F. Crush the hazelnuts and crumble the chocolate graham crackers.
Combine the nuts, cookie crumbs, cocoa powder, and melted butter and mix well.
Line the bottom of a springform pan with parchment paper, press the chocolate cookie base into the pan, and refrigerate for 10-15 minutes.
Add the cream cheese, sugar, and corn starch to a bowl and stir everything with a hand mixer. Gradually add the eggs and egg yolk.
Heat the heavy whipping cream and pour it over the chopped white chocolate. Stir the chocolate cream until the chocolate is fully melted and let it cool down for a bit before adding to the cheesecake cream. Mix everything with a hand mixer on high and pour the finished cream over the chocolate base in the pan.
Place the cake pan on the middle oven rack and place a bowl or casserole dish filled with hot water on the bottom of the oven. Bake the cake for 10 minutes at 350°F. Then reduce the temperature to 250°F and bake for 90 minutes. Let the cake cool to room temperature, or even better, refrigerate overnight.
Sprinkle sugar on top of the cake and use a culinary torch to caramelize it. Garnish with fresh raspberries.
