Ingredients

• 2 tablespoons olive oil
• 1/2 large red onion, thinly sliced
• 1 1/2 tablespoons chopped garlic
• 1 tablespoon grated lemon peel
• 1 1/2 teaspoons minced fresh rosemary
• 2 large skinless boneless chicken breast halves, cut crosswise into 1/2-inch-thick slices
• 2 10-ounce packages ready-to-use spinach leaves
• 12 ounces penne pasta, freshly cooked, 1/2 cup cooking liquid reserved
• 1 2/3 cups grated Parmesan cheese (about 5 ounces)

Instructions

1. Heat oil in heavy large pot over medium-high heat. Add onion, garlic, lemon peel and rosemary. Sauté until onion softens, about 7 minutes. Sprinkle chicken with salt and pepper. Add chicken to pot and sauté until just cooked through, about 4 minutes. Add half of spinach and toss until beginning to wilt, about 2 minutes. Add remaining spinach and toss until all spinach is wilted but still bright green, about 3 minutes longer. Mix in pasta, then 2/3 cup cheese. Moisten with reserved pasta cooking liquid by tablespoonfuls if mixture is dry. Season with salt and pepper. Serve, passing remaining 1 cup cheese separately.