Blanch the nettle leaves in boiling salted water for about ten seconds, then drain, squeeze well, and chop them. Grate the cheese crusts and place them in a bowl; add the finely chopped bread crumbs, eggs, and nettles, then mix everything until well combined. Season with pepper to taste. Shape the mixture into oblong meatballs, placing them on a sheet of parchment paper as you go. Heat plenty of oil and carefully dip in the meatballs a few at a time; fry them until they turn golden brown and slightly puff up, then drain them on paper towels.