Preheat oven to 350 degrees. Grease 13x9 inch baking dish and set aside.
In a large skillet, cook and crumble ground beef over medium heat until there is no more pink. Drain excess fat from pan. Add chopped onion, beans, tomatoes, chilies and taco seasoning. Cook for 5-10 minutes until onions are translucent and ingredients are heated through.
Cover bottom of greased baking dish with tortillas. I had to cut some in half to cover entire bottom. Pour half your meat mixture over the top. Sprinkle with shredded cheese.
Place another layer of tortillas over the meat mixture. Pour remaining meat mixture evenly over tortillas and sprinkle remaining shredded cheese on top. Place last layer of tortillas on top of the meat mixture. You can add shredded cheese to the top if you wish, but not necessary.
Cover with tin foil and bake for 30 minutes. For a crispy top, remove foil for last 10 minutes of cooking.
Serve with garnishments of guacamole, sour cream and shredded cheese! Then enjoy!