Preheat your oven to 350°F (175°C). Lightly spray an 11×7-inch (2 quart) baking dish with non-stick cooking spray or brush with olive oil. It’s essential to use a relatively small baking dish to accommodate the seitan’s expansion as it roasts.
In a large bowl, combine the vital wheat gluten, chickpea flour, onion powder, dried sage, dried rosemary, salt, and black pepper. Mix well and set aside. In a separate small bowl, whisk together the vegetable broth, soy sauce, and maple syrup. Gradually stir this mixture into the flour mixture.
Working quickly, use your hands to knead the dough just until combined. The dough will come together almost immediately and have a wet but firm and springy texture. Shape into a loaf approximately 7 inches in length. Sprinkle the seitan roast with poultry seasoning, then place it in the prepared baking dish.
In a small bowl, mix together the chicken-style broth, soy sauce, minced garlic, dried sage, dried rosemary, and dried thyme. Pour this mixture around the seitan roast in the baking dish.
Cover the baking dish tightly with aluminum foil and bake for 1 hour. Once done, transfer the roast to a serving plate and spoon the basting liquid over it. Use a serrated knife to cut into individual slices and serve hot.