1 pkg. (approx. 24) corn tortillas (flat, refrigerated, not hard ones)
2-3 lbs. browned hamburger (don't need any spices...just salt, pepper, whatever)
1 med. to lg. onion, chopped
1 c. (approx.) sliced black olives (used 3 sm. cans presliced) OPTIONAL
1 can Ro-Tel diced chilies and tomatoes
2 cans (possible 3 depending on size of casserole) Mild Enchilada Sauce (Old El Paso)
2 lb. block Velveeta cheese (easier to slice than to shred...melts anyway)

Just layer the above items over and over until casserole dish is full or you run out of ingredients. Bake at 350 degrees for about 1 hour. Can reduce ingredients to make a smaller casserole. Use 2 cans Ro-Tel chilies and tomatoes for spicier version.