Saute onions in oil, until soft and translucent, about 5 minutes.
Add tomatoes, taco seasoning, seasoned salt and green chiles. Simmer uncovered for 10-15 minutes.
In a greased 13" x 9" baking dish, arrange 1/2 of each, tortilla chips, sauce, and Jack Cheese. Repeat layers. Top with sour cream. Bake at 325 degrees F. for 30 minutes.
Sprinkle with cheddar cheese and bake 10 minutes longer.
Let stand 15 minutes before cutting into squares.