In a large saucepan, saute onions in oil until tender. Add garlic; cook 1 minute longer. Stir in the tomato sauce, tomatoes, basil, thyme, oregano and pepper. Bring to a boil. Reduce heat; cover and simmer for 20 minutes.
Meanwhile, place the milk, flour and egg in separate shallow bowls. In another shallow bowl, combine the bread crumbs, Parmesan and herb seasoning. Dip chicken in milk; roll in flour. Dip in egg; coat with crumb mixture.
In a large skillet, brown chicken in butter over medium heat until golden brown and a meat thermometer reads 170°. Sprinkle with mozzarella. Cover and cook 3-4 minutes longer or until cheese is melted. Serve over spaghetti; top with sauce. Yield: 4 servings.