To prepare the chickens: Use a paper towel to scrub the skin to remove any filaments. Use kitchen shears to cut out the backbone to spatchcock each chicken. Then cut a notch into the breastbone. Repeat with the second chicken.
To marinate the chickens: In a mixing bowl, combine the fermented red bean curd, soy sauce, dark soy sauce, oyster sauce, hoisin sauce, Shaoxing wine, five-spice powder, and white pepper. Whisk until smooth. Rub the marinade all over the chickens until evenly coated. Cover and marinate in the refrigerator overnight (8–12 hours).
To roast the chickens: Preheat the oven to 400°F (204°C). Place a roasting rack over a foil-lined roasting pan. Arrange the chickens skin-side down and roast for 15 minutes.
To roast on the other side: Flip the chickens skin-side up and roast for another 15 minutes.
To glaze the chickens and roast again: In a small bowl, whisk together the honey and warm water until well combined. Brush the honey glaze all over the chickens. Return them to the oven and roast for a final 10 minutes, or until the thickest part reaches an internal temperature of 165°F (74°C).
To serve: Remove the Char Siu Chicken from the oven and let it rest for 5–10 minutes before cutting or shredding. Serve warm.