Cook pasta according to package directions; drain. Combine eggs, crumbs, 1/2 cup onion, salt and pepper in large bowl. Add turkey; mix well. Shape into 48 meatballs. Place meatballs in ungreased 15x10x1-inch baking pan. Bake, uncovered, at 350 degrees, 15 minutes or until no longer pink inside. Drain on paper towels; set aside. Meanwhile, cook remaining onions until tender in hot oil in Dutch oven or large pot. Stir in undrained tomatoes, tomato paste and broth. Bring to boil; reduce heat. Simmer, covered, 15 minutes. Stir meatballs into sauce. Simmer, covered, 15 minutes more. Serve sauce and meatballs over hot spaghetti. Garnish with shredded Parmesan cheese and fresh oregano, if desired.