I can't think of anyone who doesn't love Nutella, and when I saw this recipe I knew I had to make it. Took it to a family dinner and everyone just raved. I gave my neighbors a slice and they immediately named me "Neighbor of the Decade". Really easy, it is very impressive-looking but most of all, It is Just Beyond Words GOOD.
Preheat oven to 350 degrees. Butter a 9-inch springform pan. Wrap the bottom of the springform pan in foil up to the rim (to prevent water from the water-bath seeping in) during final baking stage.
To make crust: whisk together cookie crumbs, ground hazelnuts, and cocoa powder in a bowl. Pour in melted butter, and stir to combine, creating a texture like wet sand. Press into bottom of pan, and up the sides about 1/2 inch. Bake for 10 minutes, then remove to cooling rack. Do not turn off oven.
(I love the crust, so I always make a little extra so it is thicker at the bottom and I can push it up the sides farther.)
While crust is cooling, make the cheesecake batter: in the bowl of a standing mixer, beat cream cheese, sour cream, and sugar until well-combined, about 2 minutes.
Add egg yolks one at a time, mixing well between each. Beat in vanilla.
In a separate Very clean bowl using a handheld mixer, beat egg whites until they hold medium-soft peaks, then fold into cheese mixture.
Reserve one cup of the cheesecake batter in the bowl; pour the rest into the cooled crust.
Mix the Nutella into the reserved batter, then drop spoonfuls of the mixture onto the surface of the batter in the filled pan. (Here I sometimes add a quarter cup of chopped toasted hazelnuts to the Nutella Mixture for crunch)
Holding a knife upright, insert it about 1/2 inch into the surface of the batter, then draw the knife back and forth across the pan, creating a marbled appearance on the cake’s surface
Create a water-bath in which to cook the cheesecake: bring a kettle of water to a boil. Place the foil wrapped springform pan in a roasting pan, and pour the boiling water into the roasting pan, surrounding the cake.
Carefully place in oven and bake for 60 to 75 minutes, or until edges begin to pull away from pan, but center is still jiggly. Remove from water-bath and cool completely on a rack.
Chill in refrigerator at least 4 hours, but ideally overnight.
When serving, you might garnish with a drizzle of Nutella or a dollop of creme fraiche.