1sauté onions in butter. Add tomato sauce and Chiles and simmer five minutes. Add oregano, milk and eggs.
2In buttered 9 x 13" casserole, layer the corn chips and Monterey Jack cheese and some of the grated cheddar cheese. Pour sauce over top. Top with sour cream and remaining cheddar cheese. Bake 30 minutes at 350°. Serves eight.