Preheat oven to 350 degrees F. Line and grease two 9 or 8-inch round cake pans with parchment paper and cooking spray and set aside. Click for the photo instructions for lining round pans with parchment paper.
Combine the sugar, flour, cocoa powder, baking soda, baking powder, and salt in a large bowl or stand mixer fitted with a whisk attachment and mix together.
Beat in the eggs, buttermilk, coffee, oil, and vanilla and beat on medium speed for 2 minutes, the batter is going to be very thin.
Evenly divide the batter between the two pans and bake the cakes for 40-45 minutes until toothpick comes clean from center.
Cool in pans for at least 10 minutes and loosen from sides of pan before transferring to a cooling rack to cool completely.
While the cakes are cooling, prepare the Nutella Frosting, then assemble and frost the cooled cakes starting with a thin crumb coat and chilling for 30 minutes before adding the final coating. Pipe additional frosting around the edge and top as desired.
Add Ferrero Rocher candies, chopped hazelnuts, and chocolate sprinkles for the final touch.