For the Broth:
In a large pot, combine chicken broth, quartered onion, sliced ginger, crushed garlic, star anise pods, cinnamon sticks, and whole cloves.
Bring to a boil, then reduce heat and simmer for 30 minutes to allow the flavors to infuse.
Strain the broth through a fine-mesh sieve into a clean pot, discarding the solids.
Stir in fish sauce, soy sauce, and brown sugar. Taste and adjust seasonings if needed.
Keep the broth warm while preparing the other components.
For the Chicken:
Preheat oven to 375°F (190°C).
In a bowl, combine vegetable oil, soy sauce, fish sauce, lime juice, minced garlic, and grated ginger to create a marinade.
Place chicken in a shallow dish and pour the marinade over it, ensuring all pieces are well coated.
Let the chicken marinate for at least 30 minutes, or up to 2 hours in the refrigerator for more flavor.
Place the marinated chicken on a baking sheet and roast for 25-30 minutes, or until the internal temperature reaches 165°F (74°C).
Allow the chicken to cool slightly, then shred it using two forks.
For the Noodle Bake:
Cook the rice noodles according to package instructions until they are al dente (slightly firm). Drain and rinse with cold water to stop the cooking process.
Preheat oven to 375°F (190°C) if not already heated.
In a large mixing bowl, combine the cooked noodles, shredded chicken, bean sprouts, sliced mushrooms, julienned carrots, chopped bok choy, sliced green onions, chopped cilantro, and torn basil leaves.
Pour about 4 cups of the prepared broth over the mixture, reserving the remaining broth for serving. Gently toss to combine all ingredients.
Transfer the mixture to a 9x13 inch baking dish, spreading it evenly.
Cover the dish with aluminum foil and bake for 30 minutes.
Remove the foil and bake for an additional 15 minutes, or until the top is slightly golden and the edges are bubbling.
To Serve:
Let the bake rest for 5-10 minutes before serving.
Serve each portion with additional warm broth poured over the top, if desired.
Garnish with fresh bean sprouts, cilantro leaves, basil leaves, sliced green onions, and lime wedges.
Offer Sriracha and hoisin sauce on the side for those who prefer additional heat or sweetness.