Cook spaghetti to desired doneness as directed on package. Drain.
Meanwhile, melt margarine in large saucepan over medium heat. Add onion and garlic; cook 2 to 3 minutes or until tender. Stir in flour, salt, oregano, basil and pepper; cook until mixture is smooth and bubbly. Gradually add milk, stirring constantly, until mixture boils and thickens.
Add 1/2 cup cheese, chicken, spinach and carrot; cook 2 to 3 minutes or until spinach is tender, stirring constantly.
Serve chicken mixture over spaghetti. Sprinkle with 1 tablespoon cheese.