This pizza is delicious although very rich. My son and son-in-law both love this pizza but prefer to have some spicy pepperoni sprinkled on top as well which adds a bite that offsets the richness of all the cheese. Quattro formaggi of course means four cheese, and traditionally those four cheeses include mozzarella, Gorgonzola, Parmesan, and a fresh creamy cheese such as Robiola or Stracchino.
The pizza quattro formaggi literally means four cheese pizza. With regards to what cheeses you use, well, that is completely up to you.