King Ranch Casserole

1 small chicken, cooked and deboned
1 small onion, chopped
1 stick margarine or butter
1 large can evaporated milk
1 can mushroom soup
1 can cream of chicken soup
Chopped jalapenos (about 5)
Shredded cheddar cheese
Corn tortillas, torn up

Sauté onion in butter. Mix in milk and soups and heat. Butter a casserole dish. Layer tortillas, chicken, soup, jalapenos, cheese. Cover and bake until bubbly and brown (350 F for approx 45-60 minutes).