Preheat oven to 350°F.
In a large skillet over medium-high heat, melt the butter. Add sausage to the pan and crumble with a wooden spoon. Once cooked, add in celery and onion, and sweat out, about 2-3 minutes. Add the bag of stuffing cubes and stir to combine. Pour in chicken stock, add cranberries and walnuts, and mix to combine.