In a large bowl, combine the spaghetti, spinach, cream, 4 tablespoons Parmesan cheese, salt, pepper and nutmeg. Place in a greased 8-in. square baking dish. Top with chicken, Swiss cheese, mushrooms and bacon.
In a small bowl, combine the eggs, ricotta, onion and garlic; spread over chicken. Sprinkle with remaining Parmesan cheese.
Bake, uncovered, at 350° for 30-35 minutes or until bubbly.