Boil chicken in water and simmer about 25 min.
Remove skin and bones and cut into bite sized pieces.
Saute mushroom in butter and use butter to grease casserole dish
Prepare white sauce (or use celery soup)
Melt butter, whisk in flour til blended. Heat milk and broth and add
to flour mix. Let boil, while whisking. Reduce and simmer 5 min.
Season to taste.
Combine all ingredients except cheese in buttered casserole. Top
with cheese and let stand in refrigerator overnight.
Bake uncovered in 300 degree oven for 1 1/2 hrs. Let sit before
Optional- Serve with cilantro, red salsa, and sour cream.