Preheat oven to 350 degrees F
Lightly butter a round 9-inch cake pan
Dust with a flour & cocoa powder mix (70% flour - 30% Cocoa powder)
In a large mixing bowl, mix together flour, sugar, cocoa, baking soda, baking powder, and salt until smooth
Add eggs, buttermilk, warm water, oil, and vanilla
Beat on a low speed until smooth
Pour the batter into the cake pan, tapping the cake pan to remove any bubbles
Bake for 30-35 minutes in a 350 degree oven until a toothpick inserted into the center comes out clean.
Cool on wire racks for 15 minutes and then remove the cake from the pan and place on the wire rack to cool
Cut the cake into 3 horizontal pieces
Brush each cake layer with Rum and espresso mixture
In a separate bowl, fold whip cream and hazelnut spread
Spread the whip cream and hazelnut spread on the top of the bottom layer
Add second layer of cake
Brush cake with Rum and espresso mixture
Spread the whip cream and hazelnut spread on the top of the middle cake layer
Add final layer of cake
Brush cake with Rum and espresso mixture
Frost entire cake (top and sides) with remaining whip cream, hazelnut spread
Sprinkle Dark chocolate over top or alternatively fresh cocoa