In a large skillet combine the pineapple juice, brown sugar, ketchup, ginger, garlic salt, cornstarch and soy sauce. Simmer all together for 5 minutes over low heat.
Place cooked chicken, bell pepper, onion, and water chestnuts in a 9x13 inch baking dish. Pour skillet mixture/sauce over the top. Cover dish with aluminum foil and bake in the preheated oven for 1 hour.
