Monterey Chicken

4 chicken breasts
1/2 cup butter, divided
1/2 cup onion, chopped
1 tsp. garlic, chopped
8 large mushrooms, sliced
2 T. flour
1/4 tsp. celery salt
1/2 tsp. pepper
1 cup chicken stock
1 1/2 cup Monterey Jack cheese

Pound 4 chicken breasts until thin. Sprinkle with salt, pepper and flour. Melt 1/4 cup butter in a large skillet and saute chicken until golden. Don't let the butter burn. Remove chicken from pan and melt 1/4 cup butter.  Saute onions, garlic, and mushrooms. Stir in 2 Tablespoons flour. Cook 1 minute. Add celery salt, pepper, and chicken stock. Cook until thick. Stir in 1/2 cup Monterey Jack cheese. Season with salt and pepper if needed.  Place chicken in baking dish. Top with onion, mushroom sauce.  Put 1 cup of Monterey Jack cheese on top. Bake uncovered at 350 for 15 minutes or until melted.