In a large sauce pot, brown 3 pounds lean ground chuck in 3 tablespoons vegetable oil, about 5 minutes. Add 2 1/2 cups chopped onions, 2 cups chopped celery ribs with leaves, and 2 cups grated carrots; cook additional 5 minutes. Stir in 3 (2 pound 3 ounce) cans tomatoes (sliced or wedged), 2 1/2 tablespoons salt, 2 tablespoons crumbled leaf oregano, 2 teaspoons pepper, and 1 1/2 teaspoons garlic powder. Bring to boil. Lower heat and cover; simmer 1 hour.
Meanwhile, cook 2 pounds macaroni shells or 2 pounds elbow macaroni or 2 pounds noodles, according to package directions; drain and set aside. When sauce is done, stir in cooked pasta and 2 (10 ounce) packages frozen chopped spinach (thawed); mix thoroughly. Put into 2 large (13 x 9 x 3 inch or larger) casseroles; sprinkle 2 cups grated Parmesan cheese on top and put in oven (at 350 degrees) 30 minutes or until bubbly.
When ready to serve, put out 2 loaves (large) of Italian bread and a lettuce salad (three heads of lettuce) with oil and vinegar. And, of course, to be served with red wine. If you should only want to serve 10 people, this can also be frozen and used at a later date.