Sautee celery, peppers, mushrooms, and onions in olive oil for 5- 7 minutes until crispy. Debone and remove skin from rotisserie chicken. Shread white and dark meat and mix together and put in bowl. Mix salt, garlic, pepper, water chestnuts and light mayonaise. Put into sprayed baking dish. Then melt butter and combine with bread crumbs and sprinkle atop mixture in baking dish. Then top with shredded sharp cheddar cheese. Bake at 350 degrees for 20 minutes.