The hazelnut is not an ingredient one immediately associates with Italian cookery, yet they are definitely rooted in our food culture: or instance, I have never come across a gelateria that does not have nocciola (hazelnut) flavour, one of the best actually (and, as you know, gelaterie are everywhere in Italy), you can often spot a roasted hazelnut atop pasticcini, the diminutive Italian pastries, and biscuits, a signal that what you are going to taste contains the nuts. There is Frangelico too, a hazelnut liqueur from Piemonte that can elevate anything it is drizzled over to new heights, and, well, then there is Nutella, one of the most famous Italian foods, a mix of chocolate and (not so many) hazelnuts and other, more or less, insalubrious ingredients. If you travel to central Italy, in particular in the Tuscia region of Lazio and in Umbria, you will see vast, intensively cultivated hazelnut groves, which contribute hugely to the local economy but that are also cause for concern.  What was once a minor crop has become very important, to the point that Italy is now the world’s second-largest producer, for better or worse. Here an article in Italian too.