nocino

Made by steeping green walnuts and spices in alcohol, nocino is black and a little bitter (it's the green husks that also make walnut stain for wood), but prized nonetheless. Much of it is home made, but among the commercial versions perhaps the most famous is nocino del Modinese (Here's a recipe, adapted from Pellegrino Artusi)

In parts of Tuscany, Lazio and Campania the same thing is called nocillo or nucillo: nucillo é curti is made from walnuts harvested on the slopes of Mount Vesuvius.

A similar liqueur from Emilia that also uses hazelnuts is called nocello.