"Chocolate and hazelnut" was the response I received from a friend after offering to bake her a special 40th birthday cake. I had recommended she peek through the "Cakes" page of this site and see if she developed any particular requests and she lighted upon the 9-layer chocolate-hazelnut cake I made for Will's birthday last year.
Being as I never like to repeat my cakes exactly, I took it as an opportunity to modify the satsuma cake from a few weeks ago with hazelnuts instead of almonds, and reduce some of the nuts in place of a bit of flour. Although both cakes were very good, I strongly preferred this version with flour... it had a finer texture - not so grainy, and less dense.
The orange-hazelnut layers were sandwiched between chocolate genoise soaked in Frangelico syrup. I used the recipe from The Cake Bible and actually had to make it twice because it overbaked the first time. The second time I watched the time very closely, especially as I was baking in three 8-inch rounds instead of one springform pan. Genoise is intended for the top and bottom "crusts" to be cut off. It can be hard to do that, and then cut into layers evenly, even with a cake slicer. At the same time, baking shallower layers can cause each layer to not bake as evenly, and to be so thin as to leave little behind after trimming. Genoise must be soaked in syrup in order to have any moistness, texture, and really - flavor and sweetness. Although I didn't have a taste of the final assembled cake, I liked the idea of the moist but textural nut cake layered against a moist yet airy genoise. The Frangelico syrup can be replaced by any flavor of your choice, but is an appropriate selection to pair with the nuts in the orange cake.
The remaining recipes also came from The Cake Bible, with whipped ganache between the layers (using about 60% chocolate) and bittersweet ganache (using about 75% chocolate) for the glaze. It's very challenging for me to get a smooth ganache finish down the sides of the cake, though the top gets quite glossy and seamless. If I'd had enough chocolate to make extra whipped ganache, I would frost the sides evenly with that, and then allow the ganache to drizzle over it and drip down the sides without worrying about trying to get a full coverage from the glaze.
I pressed chopped hazelnuts part-way up the sides of the cake around the bottom circumference border, and topped with whole toasted hazelnuts and chocolate shavings.