In an 8x8 pan (NOT muffin tins), prepare muffin mix according to package directions.
Preheat oven to 350 degrees F (175 degrees C).
In a large bowl, combine shredded chicken, cream of chicken soup, cream of celery soup, salt and pepper and mix well. Pour mixture into a lightly greased 9x13 inch baking dish and crumble baked muffin mix on top.
Bake at 350 degrees F (175 degrees C) for 30 minutes or until bubbly.