Place potatoes in a Dutch oven and cover with water.

Bring to a boil. Reduce heat; cover and cook for 10-15 minutes or until tender.

Meanwhile, in a large skillet, saute celery and onion in butter until tender.

Remove from the heat.

In a large bowl, combine the stuffing cubes, poultry seasoning and sage.

Stir in broth and celery mixture.

Transfer to a greased 13-in. x 9-in. baking dish.

In another large bowl, combine the turkey, soup, garlic powder and 1/4 cup sour cream; spoon over stuffing mixture.

Drain potatoes; mash in a large.

Beat in the cream cheese, pepper, salt and remaining sour cream; spread over turkey mixture. Sprinkle with cheese.

Bake, uncovered, at 350° for 30-35 minutes or until heated through.