In a large skillet, cook beef and onion over medium heat until no longer pink. Add garlic; cook 1 minute longer. Drain. Stir in spaghetti sauce, diced tomatoes, mushrooms and Italian seasoning. Bring to a boil. Reduce heat; simmer, uncovered, 20 minutes., Meanwhile, preheat oven to 350°. Cook pasta according to package directions; drain. Add to beef mixture and gently stir in sliced plum tomatoes. , Transfer to an ungreased 13x9-in. baking dish. Sprinkle with cheeses. Bake 25-30 minutes or until bubbly and heated through.