Enchilada Casserole

I got this idea off of Picky Palate.  She made something similar using chicken enchilada ingredients so I decided to try it with ground beef and red sauce.  This was so easy and tasted so good that I might never make regular enchiladas again.  Ok, so I actually made enchiladas yesterday (honey/lime) and rolled them, so I guess that's not true.  But a casserole sure is nice when you're short on time.

1 lb. lean ground beef
1 onion, chopped
Red enchilada sauce (I used two small jars from Trader Joe's)
6-8 corn tortillas, torn into pieces
Shredded cheese (I used colby/jack)

*Brown ground beef with onion on stove.  Season with salt/pepper/garlic powder.  Add enchilada sauce and let simmer.  Tear up corn tortillas into bite-size pieces.  Pour meat mixture into a 9x13 pan.  Add tortillas and mix together really well.  Cover the top with cheese and bake at 350 for 25-30 minutes.