I drew inspiration for the outside of the cake from Rose Levy Beranbaum's book Rose's Heavenly Cakes, specifically her "chocolate tomato cake." The cake is surrounded by Pirouette cookies of varying heights. Each of these cookies is topped by a small dollop of red frosting to act as little candles. If you want to make this cake for an age-conscious birthday person, please note that I had to use 67 cookies to completely surround the cake.
The inside of the cake, however, was my own creation. I used my basic chocolate cake recipe. This cake normally uses 1.5 cups of coffee to accentuate and darken the chocolate flavor, but I substituted one-third of that with Frangelico, a hazelnut liqueur. As a third surprise layer, I baked my traditional banana bread recipe in a round cake pan. The banana bread stays wonderfully moist and I may use it to make a full cake one day.
So far, this cake is not very Nutella-y. That's where the frosting comes in to bind it all together, both in construction and in flavor. I mixed together 1 cup of Nutella with 3 cups of powdered sugar and 2 tablespoons of milk to produce just enough frosting to cover this 3-layer, 9-inch cake. On top of all this, I placed some toasted, chopped hazelnuts. The result is a behemoth cake that astounded everyone. I have a hard time deciding if it had too many elements or just enough to make it a really good cake. All of the flavors blended together beautifully to produce a cake that will be tough to beat for the next birthday.