- Grease a ring or a baking dish with butter, and sprinkle with cocoa; place the mold on parchment.
- Sift all the dry ingredients into a bowl; add the egg, milk, vegetable oil and butter. Whip at medium mixer speed for 3-4 minutes.
- Add the chopped hazelnuts.
- Transfer the mass to a mold, and bake in a 20cm (7.87 inch) ring at 338F (170C) for 10-15 minutes.
- Preheat the oven to 266F (130C). Be sure to put a baking sheet with hot water on the bottom of the oven.
- Mix the cream cheese well with sugar; add the eggs, stirring well each time. Pour in the cream and vanilla essence, and mix well.
- Pour the cheese mass over the chocolate base, and bake for 1 hour. The center should shake a little.
- Cool the finished cheesecake, and refrigerate it for at least 6 hours.
Cut the finished cheesecake, pipe Nutella on top, and sprinkle it with grated chocolate and hazelnuts.