In a 12-inch, heavy skillet over medium heat, melt butter until hot but not smoking. Stir in shallots and celery, cover, and cook, stirring occasionally, until soft, 15 to 20 minutes.
Transfer to large bowl and add stuffing cubes, parsley, celery salt, sage, rosemary, thyme, salt and pepper. Stir in 1 1/4 cups hot stock.
If using to stuff turkey: Use immediately to fill cavities and spread remainder in baking dish as directed in your preferred turkey recipe.
If baking recipe as side dish: Preheat oven to 350°F and butter a 3-quart casserole or 9- by 13-inch baking dish. Transfer stuffing to dish and drizzle with 1/2 cup hot stock. Cover with aluminum foil and bake until heated through, about 30 minutes. Uncover and bake until top is slightly crisp and golden, about 10 minutes longer. Serve immediately.