In large skillet, melt butter/margarine and add onion. Cook until slightly transparent. Add soups, milk, green chillies and salsa. Cook over low heat until well blended.
In a greased 9 x 13" baking dish, put 1/2 of the crushed tortilla chips. After mixing the chicken with the cumin and cayenne, add 1 cup to the top of the chips. Pour 1/2 soup mixture over this and add 1/2 the grated cheese. Repeat the layers. Bake at 350 degrees for 25 - 30 minutes or until bubbly. This is excellent!!!