In 12-inch heavy skillet over medium heat, add butter and cook until melted. Add bacon to skillet and cook 5-10 minutes until bacon is cooked through and starting to get crispy. (There should be a lot of liquid in the pan.)
Stir in onion and celery, cover, and cook, stirring occasionally for about 5-10 minutes. You want onions to be translucent.
Transfer to a large bowl (the bigger the better) and add bread cubes, parsley, celery salt, sage, rosemary, thyme, cranberries, salt, and pepper.
Stir in 3 1/2 cups warm chicken stock.
If using to stuff turkey: Use immediately to fill cavities of turkey.
If baking entire recipe as side dish: Preheat oven to 350°F.
Transfer all ingredients back to original skillet. Drizzle with an additional 1/2 cup hot stock. Cover with aluminum foil and bake until heated through, about 30 minutes.
Serve immediately.