Prep: Preheat oven to 350°F. Grease a 9x13" baking dish or 3-quart casserole dish.
Make the broth: If you're using a vegan chicken bouillon that comes in paste or cube form, dissolve in in just boiled water to prepare the broth.
2 ½ cups vegan chicken-style broth
Sauté the veg: Melt the vegan butter in a large skillet over medium-high heat. Add in the diced onions and celery and sauté until very soft, about 8-10 minutes. Add the garlic and cook for 1-2 minutes more, until fragrant. Stir in the poultry seasoning and fresh herbs, and cook for about 30 seconds.
1/2 cup vegan butter, 2 cups finely diced onion, 2 cups finely diced celery, 4-6 cloves garlic, 2 teaspoons poultry seasoning, 1 tablespoon fresh sage, 2 teaspoons fresh thyme leaves, 1 teaspoon fresh rosemary, salt and pepper
Toss the bread: Transfer bread cubes to a large mixing bowl. (You can mix directly in your pan if using a big Dutch oven or a deep sauté pan). Pour the onion mixture over the bread cubes. Make sure to scrape in all the butter. Toss to combine.
Moisten the stuffing: Pour in vegetable broth a little at a time, gently tossing after each addition, until the bread is evenly moistened (but not soggy). Crustier loaves soak up more broth, while lighter breads need less. Taste and season with salt and pepper.
Bake: Transfer to prepared pan and cover with foil. Bake for 35 minutes. Uncover and bake 10-15 minutes more, until as golden and crispy on top as you like.