Combine the salsa, cream of chicken soup, cream of mushroom soup, evaporated milk, & green chilies in saucepan. Heat and stir until thoroughly blended and warm.
Spray the bottom of a 9 x 13 inch baking pan with vegetable spray. Line the bottom of the pan with 18 tortilla chips. Place a layer of the chicken on the tortillas. Add a layer of sauce mixture, onions and a layer of cheese. Repeat layers, ending with cheese.