Preheat oven to 350ºF.

Sift together the flour, cocoa powder, baking soda, and salt into a bowl. In another bowl, with an electric mixer on medium-high speed, beat the butter and sugars until light and fluffy, about 2 to 3 minutes. Add the eggs and vanilla and beat until combined. Add the flour mixture in 3 additions, alternating with water and buttermilk, beating on low speed until just combined; scape down the sides of the bowl as needed. Beat on medium-high speed just until no traces of flour remain, about 30 seconds; do not overbeat.

Divide the batter evenly into 2 8-inch round pans that have been greased and floured. Bake for about 30 minutes or until an inserted toothpick comes out clean.

To make the cream, whip together cheese, sugar, vanilla, and heavy whipping cream with electric beaters until peaks form. I chill a stainless steel bowl in the freezer so it whips faster. Add 1 cup Nutella and beat until well blended.

Microwave the remaining 1 1/2 cups Nutella (for the inside layer) for 30 seconds or until it is easy to spread but not too loose that it will run off your cake. Spread evenly over the bottom layer of the cake and set in the freezer for 5 to 10 minutes. Once the Nutella layer sets, spread a layer of chocolate hazelnut whipped cream over it. Top with other cake layer and frost the sides and top of the cake with cream. Top with chopped hazelnuts. Feel free to pipe a design around the top and bottom sides of the cake; you will have more than enough cream to do so!