Matt,
did you see the picture that I posted of the sfincione? There is no mozzarella in it, but small pieces of caciocavallo on it. If you like, try frying the diced onions lightly with oil until transparent, then you take the onions out and mix in toasted crumbs, salt,pepper,oregano, mix all and then spoon it on the sauce, then on top of all that, you position pieces of anchovies so that on every slice you will get a taste of the anchovies. it looks better too!