Beef Enchiladas

I'm listing this here because my husband and kids love this dish... BUT it is NOT authentic at all.  This is my mother-in-law's recipe for enchiladas.  I kind of think of it as more of a ground beef throw-it-together casserole. 
1 1/2 lbs. ground beef
1 med onion, chopped
salt
pepper
2 pkg. brown gravy
1 can sliced olives
flour tortillas
3 4oz. cans of tomato sauce
Cheddar cheese

Brown hamburger with diced onion.  Season with salt and pepper to taste.  In a small sauce pan, cook brown gravy according to packet directions.  Pour gravy into hamburger.  Add sliced olives.  In a 9x13 casserole cover the bottom with tomato sauce.  Fill tortilla with meat filling, roll, and roll it in tomato sauce.  Repeat until casserole is full.  Pour the rest of the sauce over the enchiladas and cover with grated cheese.  Back in 350 oven until cheese is melted and bubbly.  (About 5-10 minutes)