Preheat your oven to 350°F (175°C).
Spread the cubed bread on a baking sheet and bake for 10 - 15 minutes, or until bread is dry and slightly crispy. Remove from the oven and set it aside.
In a large skillet, melt the vegan butter or heat the olive oil over medium heat.
Add the chopped onion and celery and sauté for about 5 minutes, or until they become tender.
If you're using mushrooms, add them to the skillet and cook for an additional 5 minutes, until they soften and release their moisture.
Stir in the minced garlic and cook for another minute until fragrant.
In a large mixing bowl, combine the dried bread cubes with the sautéed vegetables and chopped fresh parsley. If you're using chopped nuts, add them to the mixture at this point.
In a separate bowl, whisk together the vegetable broth, poultry seasoning, dried sage, dried thyme, dried rosemary, salt, and black pepper.
Pour the seasoned vegetable broth mixture over the bread and vegetables in the large bowl. Toss everything together until the bread is evenly coated.
Transfer the stuffing mixture to a greased baking dish.
Cover the baking dish with aluminum foil and bake in the preheated oven for about 30 minutes.
Remove the foil and bake for an additional 15-20 minutes or until the stuffing is golden brown and crispy on top.
Serve as a side dish for dinner or your holiday feast.