Preheat the oven to 350°F. Spray a 13 x 9 inch baking dish with cooking spray.Set aside.
In a large skillet, met the butter. Add diced celery, onion and bell pepper. Cook for 5 minutes until softened and beginning to brown.
Add cornbread stuffing mix, 2 cups of chicken stock, 1/2 tsp poultry seasoning and 1/4 tsp black pepper. Stir well and remove from the heat. Set aside.
In a mixing whisk together both soups, milk, mayonnaise, Parmesan cheese, garlic salt, 1 1/2 tsp poultry seasoning and 1/4 tsp black pepper. Mix well.
Stir 1/2 cup of the creamed mixture into the cornbread dressing.
To assemble, spread 1/2 of the cornbread dressing into the bottom of the baking dish. Arrange the chopped chicken on top.
Drizzle evenly with the creamed mixture and finish with the remaining cornbread dressing.
Bake covered with foil for 30 minutes then uncover and bake for an additional 15 minutes or until golden and bubbly around the edge.