Beef Enchilada Casserole

3 lbs. ground beef
3 pkgs. taco seasoning mix
2 cans enchilada sauce
2 cans cream of mushroom soup
1 can tomato soup
1 cup chopped onion
4 cups shredded cheddar cheese
3 pkgs. corn tortillas
sour cream

Brown meat; drain grease. Add taco seasoning mix and required amount of water on pkg. Simmer 15 minutes.
In large saucepan mix enchilada sauce, cream of mushroom and tomato soups. Heat on low heat stirring to remove all lumps.
Layer tortillas in 1 deep casserole or 2 shallow casserole pans, covering bottom. Place layer of meat mixture, chopped onions, cheese and sauce.
Cover top with a layer of tortillas, sauce and cheese. Place in 350* oven for 35 minutes. Cut in squares and serve.
Top with sour cream if desired.