Place the butter in a large, deep skillet or Dutch oven over medium heat. When melted, add the onion and celery and cook, stirring, until it softens, about 5 minutes.
Add the nuts and cook, stirring almost constantly, until they begin to brown, about 3 minutes.
Add the bread crumbs and the sage and toss to mix. Turn the heat down to low. Add the salt, pepper, and scallion. Toss again; taste and adjust the seasoning. Add the parsley and stir. Turn off the heat.
You can serve immediately. If you are serving it later, p¼lace the stuffing in a casserole dish (3 quart or 9x13-inch) or keep in the enameled cast iron dutch oven with the lid on and heat in a warm oven (200° Fahrenheit’s).
If you want the stuffing to have a more soft texture, you can make it the day before, cool and place it in the fridge covered. The next day, place the stuffing in a casserole dish (3 quart or 9x13-inch) and bake for about 45 minutes, or until crisp and heated through.