I wish I had asked my Nonna when she was still alive, but I neglected to do so. Therefore, I only have my memory of her "polpettone." (=meatball, Roman style). They definitely had ground veal, ground beef, maybe ground pork, in addition to chopped hard-boiled eggs, raisins, and pignoli (pine) nuts. And I am sure that breadcrumbs and various seasonings were added.
Anyone have a recipe like this? They were absolutely delicious.