This is our church favorite as well as family. Everyone wonders what the secret ingredient is. (Who would actually make enchiladas with chicken noodle soup?) Me for one... I have one in the oven as I type.
Brown hamburger,drain, add soups, enchilada sauce and chopped onion. Simmer 10-15 minutes then add the tortilla pieces and simmer several more minutes so the tortillas soak up some of the juice. Add a handful of grated cheese, let melt. Pour mixture into a large casserole dish, cover with grated cheese and bake 300* just long enough to melt the cheese.
This is excellent for a large covered dish gathering, and addicting.