Roasted garlic and Pecorino Romano add flavor to this rich, creamy sauce that will satisfy just about anyone at your dinner table.
Trim the top thirds of garlic heads. Set on parchment-lined foil, drizzle with olive oil, top with thyme, and wrap. Roast at 400 degrees for 1 hour. Cook penne, reserving 3/4 cup pasta water. Squeeze garlic out of skins and heat in a skillet with pasta water and cheese, whisking until thick and creamy. Stir in cream, and penne. Season, and top with greens.