baked spaghetti recipe

300 grams (10.5 ounces) spaghetti - 2 cups marinara sauce (store-bought or homemade) - 1 cup ricotta cheese - 1 cup shredded mozzarella cheese - 1/2 cup grated Parmesan cheese - 1/2 cup chopped fresh basil or parsley - 1 pound ground beef or Italian sausage (optional) - 1 medium onion, chopped - 2 cloves garlic, minced - 1 tablespoon olive oil - Salt and pepper to taste