This casserole varies according to the tortillas, cheese, and other ingredients I have on hand.
Brown ground beef and onions in a pan. Add chile powder, cumin, and ground pepper (salt optional).
Add tomato sauce, simmered with chile and cumin, to moisten. A more authentic version uses a sauce made of 1 cup of dried red chiles simmered in ¾ cup of water with onions and some salt. When the chiles are soft, cool the mixture slightly then puree until smooth.
This casserole can be made either of two ways--you can stack the tortillas (corn or flour) with the meat filling and grated cheese in between them and bake the whole thing in a casserole dish; or you can fill the tortillas with the filling and grated cheese and roll them up and bake them in an oblong pyrex dish. In either case, top with a little filling or sauce and sprinkle with a bit more grated cheese.
Cover the dish with foil, bake about 40 minutes at 350. Uncover and bake for 5 more minutes. Note: You can sneak all kinds of leftovers into this casserole. I have added rice, chopped fresh tomatoes, corn, and a few things I won't admit to.