This hazelnut caramel cake recipe is a decadent dessert that is perfect for special occasions. The cake is made with layers of hazelnut sponge cake and a creamy caramel filling. The frosting is a rich and creamy caramel buttercream that is drizzled over the top of the cake. The cake is finished with a sprinkle of chopped hazelnuts and a dusting of powdered sugar. This recipe is a bit more advanced, but the end result is well worth the effort.