Order a Margherita at the best pizzerias of Naples and you typically get a pizza topped with fior di latte, a mozzarella made from cow’s milk. Don’t believe any Neapolitan who tells you the only mozzarella his brethren will tolerate on a pizza is from the milk of domestic water buffalo.

The boast is easily forgiven: The Neapolitans are justly proud of their Mozzarella di Bufala Campana DOP, one of the most prized cheeses in Italy. Five producers in Naples and another 40 in nearby Caserta produce buffalo mozzarella conforming to the strict regulations set by its trademark DOP – Denominazione di Origine Protetta (“Protected Designation of Origin”).

When Neapolitans do order Mozzarella di Bufala Campana DOP on their pizza it’s usually set against fresh pomodorini (cherry tomatoes) rather a sauce made from tinned (canned) plum tomatoes. This pizza displays the classic Margherita’s Italian tricolore – basil for green, mozzarella for white, tomato for red – but is listed differently on menus. Often it’s designated as ‘Margherita Extra’, ‘Regina Margherita’ or simply ‘La Regina’ – “the Queen”. Sometimes it takes its name from its description, as in ‘Pizza con Mozzarella di Bufala e Pomodorini’. The Pizzeria Sorbillo in Naples employs the shorthand ‘DOC’, as in Denominazione di Origine Controllata, a distinction Mozzarella di Bufala Campana was granted in 1993. The mozza’s status was upgraded in 1996 from DOC to DOP but the name stuck. London’s Princi is more up-to-date, calling the same pizza ‘DOP’.

The straight dope on Margherita pizza in Naples is, with few exceptions, as follows:

If the mozzarella is from cow’s milk it goes on the pizza atop a layer of red sauce consisting of peeled plum tomatoes taken from a tin. If the mozzarella is from buffalo milk it is distributed over the dough in slices, cubes or torn pieces and then topped with slices of fresh tomatoes whenever good ones are in season and available. We’re talking little tomatoes, usually pomodorini but sometimes datterini (little dates) or fragolini (grapes).

Why fresh tomatoes? Most pizzaioli will tell you they provide buffalo mozzarella with greater stability. If the mozzarella di bufala is fresh and of good quality it is naturally juicy and, when subjected to the intense heat of a wood-fired oven, as molten as lava from Mount Vesuvius. If the flow of milky cheese juice runs over a bed of hot tomato sauce, rather than around fresh tomatoes, the pizza surface gets very runny. Quickly the mix of white and red liquids runneth over. As a pizza cheese mozzarella di bufala thrives on dry ground.