Preheat the oven to 350ºF. Spray a 9-inch springform pan with nonstick cooking spray. Prepare the brownie mix according to package instructions. Pour batter into pan and bake for 30-35 minutes, or until a toothpick inserted in the center comes out clean. Allow to cool completely.

In a standmixer fitted with the whisk attachment, whip the heavy cream until soft peaks form. Transfer whipped cream to a separate bowl, return bowl to mixer, and switch whisk attachment out for paddle attachment.

Beat the cream cheese, Nutella, and powdered sugar together until smooth. Add a third of the whipped cream to the bowl, mixing until combined. Remove bowl from mixer, and fold in the rest of the whipped cream until incorporated. Spread mixture evenly on top of the brownie layer. Refrigerate for at least 6 hours, preferably overnight.

Place chocolate in a medium bowl. Pour heavy cream into a saucepan, and heat until it begins to boil. Immediately pour hot cream over the chocolate, cover with plastic wrap, and allow to sit for 5 minutes. Remove plastic and stir until smooth. Pour ganache on top of cheesecake layer, spreading out evenly with an offset spatula or knife. Refrigerate while making the whipped cream.

In the chilled* bowl of a stand mixer fitted with the whisk attachment (or in a bowl with a beater), whip the heavy cream, powdered sugar, and cocoa powder together until stiff peaks form. Transfer whipped cream to a pastry bag fitted with a star tip, and pipe onto cheesecake as desired. Decorate with Ferrero Rocher chocolates. Slice and enjoy!