Orange and hazelnuts are a winning combination in this insanely moist cake. If you can find hazelnut flour, replace the whole hazelnuts with 2 cups of the flour and your cake will be a little more refined with a tighter crumb. That said, I used whole hazelnuts and ground them in a food processor which resulted in a rustic cake with a great nutty texture and chunkiness that I adored. Be sure to make the syrup and brush the entire amount on the cake. It really does add something special. One last note, I used hazelnut oil in my recipe to boost the hazelnut flavor but you can’t find it, just use an equal amount of olive oil as a replacement.