Final answer:
Pecorino Romano is commonly used to garnish spicy rigatoni, giving the dish a sharp and salty flavor that balances its spicy character.
Step-by-step explanation:
When garnishing spicy rigatoni, a popular choice of cheese is Pecorino Romano. This cheese offers a sharp, salty flavor that complements the heat of the spicy sauce, balancing the flavor profile of the dish. In some recipes, Parmesan cheese, known for its nutty and savory taste, may also be used depending on personal preference or regional variations.