1. To prepare marinara sauce, heat olive oil in a large, heavy saucepan over medium heat. Add onion and saute until translucent. Add garlic and saute 1 min. Add tomatoes, tomato sauce, bouillon cubes, basil, oregano, parsley and sugar. Stir well. Simmer over low heat. 30 minutes, stirring occasionally. Add salt and pepper. Makes about 6 cups.
2. Preheat oven to 350 F
3. Toss cooked pasta with olive oil and set aside
4. Combine spinach with water in a large saucepan over medium heat. Simmer, covered, until spinach is wilted, 3 to 5 minutes. Drain well and squeeze spinach to remove excess moisture. Finely chop spinach.
5. Combine mozzarella, ricotta, eggs, garlic, spinach, 1/2 cup Parmesan, nutmeg, salt and pepper in a large bowl. Stir to blend. Generously stuff pasta shells with cheese mixture. Place shells in 2 (13x9 inch) baking dishes and cover with marinara sauce. Sprinkle evenly with remaining Parmesan cheese and parsley.
6. Bake 25 to 30 min, until cheese is melted and sauce is hot and bubbly. Let cool 5 to 10 min before serving.