American pizza often has vegetable oil or shortening (often, but not always, olive oil) mixed into the dough; this is not as common in Italian recipes (for example, the pizza dough recipe in the influential Italian cookbook Il cucchiaio d'argento does not use oil). This can range from a small amount in relatively lean doughs, such as New York style, to a very large amount in some recipes for Chicago-style deep-dish dough. In addition, American pizza (at least thin-crust) is often made with a very high-gluten flour (often 13–14% protein content) of the type also used to make bagels; this type of flour allows the dough to be stretched rather thinly without tearing, similar to strudel or phyllo dough.
Various toppings may be added, most typically:
Tomato sauce usually replaces the tomato mixture used on Italian-style pizzas, and is usually a fairly heavily seasoned, smooth sauce with a low water content. On some variants without tomatoes, pesto, alfredo and barbecue sauce are also used.
In some pizza recipes the tomato sauce is omitted (termed "white pizza"), or replaced with another sauce (usually garlic butter, but sauces can also be made with spinach or onions). In the Philadelphia area there are also tomato pies—sauce only, or sauce with ripe Roma tomatoes and spices but no cheese—and upside-down pizzas, i.e., the cheese on the bottom and topped with sauce. Pizza is normally eaten hot (typically at lunch or dinner), but is sometimes eaten as cold leftovers for breakfast.