Pasta alla carbonara (usually spaghetti, but occasionally linguine or bucatini) is an Italian pasta dish based on eggs, pecorino romano, guanciale, and black pepper. It was invented in the middle of the 20th century.
The recipes vary, though all agree that cheese (parmesan, pecorino, or a combination), egg yolks (or whole eggs), cured fatty pork (guanciale usually preferred to pancetta) and black pepper are basic. The pork is fried in fat (olive oil or lard); a mixture of eggs, cheese, and butter or olive oil is combined with the hot pasta, cooking the eggs; the pork is then added to the pasta. Guanciale is the most usual meat, but pancetta is also used. Cream is not used in Italian recipes, but is used in the United States, France and England.
Some American recipes add salt and/or garlic to taste; with peas added for color. Yet another American version includes mushrooms. Most of these preparations have more sauce than the Italian versions, and resemble fettuccine alfredo.
In all versions of the recipe, the eggs are added to the sauce raw, and cook with the heat of the pasta itself.
The dish was obscure before the Second World War, and it is not present in Ada Boni's classic book La Cucina Romana, which was published in 1927. It is thought to have originated in the hills outside Rome, not in the city itself. Its popularity began after the Second World War, when many Italians were eating eggs and bacon supplied by troops from the United States. It also became popular among American troops stationed in Italy; upon their return home, they popularized spaghetti alla carbonara in North America.