Preheat oven to 375 degrees and grease a 11x7 inch baking dish. Cook beef and onion until onions are transparent and beef is no longer pink. Drain. Stir in taco sauce, water, chilies and seasoning mix.Cook over low heat for 3 to 4 minutes. Layer half of the broken shells on the bottom of prepared baking dish. Cover with half of meat mixture; sprinkle with 1 c. cheese. Repeat with remaining ingrediants. Bake for 20-25 minutes or until bubbly and cheese is melted.
Serve with lettuce, black olives, tomatoes, sour cream or guacamole. Your choices are unlimited.