Rigatoni con la pajata is a classic dish of the Roman cucina povera. La pajata is a term referring to intestines of calves who were only fed with their mothers' milk and have never eaten grass. The intestines are cleaned and skinned, but the milk they drank is left inside - when cooked, the combination of the heat and the enzymes coagulates it, thus creating a thick, creamy, ricotta-like sauce.
Nowadays there are not many places that keep this dish on their menus, but those who do have their devotees, claiming that the pajata cooked with onions, celery, carrots, tomatoes, white wine, lardo, and spices served over rigatoni is a true delicacy.