Boil pasta until al dente (cooking time will probably be less than package directions, so test for doneness). Drain. Heat olive oil in a large pan over medium-high heat; add chicken and sauté 2 to 3 minutes until nearly done.
Add Alfredo Sauce, spinach, mozzarella and Parmesan cheeses. Cook, stirring, until cheese is melted and sauce is heated through. Toss with pasta and garnish with chopped parsley.
In a pot over medium heat, place water, half-and-half, cream and garlic and bring almost to a boil. In a separate bowl, combine flour and oil to make a paste.
Add 1/4 cup of hot cream mixture to the paste, and stir until smooth. Add paste to cream sauce in pot, whisking, until sauce thickens. If necessary to smooth out sauce, purée in a blender or food processor. Season to taste with salt and pepper.
Makes 3 cups.Makes 6 Source: