As I traveled throughout Italy, I saw how fat determines the particular flavors of regional cooking. In the North, where pastures and the dairy cattle they sustain are abundant, cooks use butter, cream, and rich cheeses readily in dishes such as polenta, tagliatelle Bolognese, and risotto. In the South and on the coasts, where olive trees flourish, olive oil is used in everything from seafood dishes to pastas and even desserts such as olive oil gelato.