Step 1

Melt the butter in a large pot over medium heat. Add the celery and cook, stirring occasionally, until tender, 5 to 7 minutes. Add the broth and soup mix, increase the heat to high, and bring to a boil. Remove from the heat, add the croutons, and toss until all the croutons are evenly moistened.

Step 2

If serving immediately: Cover and let the stuffing stand for 5 minutes. Serve warm.

Step 3

If baking: Arrange a rack in the middle of the oven and heat to 350°F. Coat a 9x13-inch baking dish with butter. Transfer the stuffing to the dish, spread into an even layer, and dot with 2 tablespoons of butter that are cut into small pieces. Butter a piece of aluminum foil and cover the baking dish with it, buttered-side down. Bake until warmed through, about 20 minutes. Uncover and continue baking until the top is crisp, 5 to 10 minutes more.