We made one of these for a customer whose wife loves Ferrero Rocher candy and the result was so beautiful and yummy that we decided to add it to our menu.  The cake has four layers of chocolate cake.  Between the layers, we spread hazelnut buttercream topped with pieces of hazelnut wafers to add a bit of crunch like the candy.  We frost it with hazelnut buttercream, cover the sides with chopped hazelnuts, then decorate the top with dollops of hazelnut buttercream and several of the candies.  Truly decadent. 🙂