Stir the rice into a medium pot of boiling, salted water and cook until almost done, about 15 minutes. Stir in the peas. Cook until the peas and rice are just done, about 2 minutes longer.
Drain.
Put the rice and peas back in the hot pot. Stir in the mozzarella, Parmesan, butter, prosciutto, salt, and parsley.
Serve immediately.
Variations : Vary the herb here if you have access to a good fresh one. Chopped mint, chervil,sage, or fennel leaves would all be excellent. : For a sharper-tasting dish, substitute 1/2 cup grated Pecorino Romano for the grated Parmesan, or use a combination of the two.
Fresh Mozzarella: Fresh mozzarella is a soft, mild white cheese that combines well with strong-flavored ingredients. The cheese, which is formed into a ball and usually packed floating in water in a plastic tub, is available both salted and unsalted. We find the unsalted variety too bland; a light salting brings out the cheese's elusive fresh-milk flavor.
Wine Recommendation: The traditional style of Italian white wines is crisp, clean, light-bodied, and fairly neutral in flavor--an ideal combination that won't overpower this dish. Soave, Frascati, and Orvieto will all work well, but a Vernaccia di San Gimignano, with its slightly fuller body and almond aroma, will be best of all.
