First keep frozen duck to thaw in the fridge for 2-3 days. Then bring the duck to room temperature for 1 hour before cooking. Rinse the duck in and out with cool water then pat dry in and out with paper towels.

Line a sheet pan with aluminum foil and place an oven-safe rack on top. Preheat oven to 400℉.

Remove excess fat from the duck cavity. Trim the duck neck and reserve for stock. Use a small knife to poke small holes all over the duck breasts.

Drizzle the olive oil all over the duck and rub the oil on the bird to ensure it coats the bird. In a small bowl, mix together the salt, pepper, chicken bouillon powder, onion powder, garlic powder, dried thyme, and fresh rosemary. Sprinkle the seasoning all over the duck and rub it on the skin of the duck and in the cavity of the duck. Stuff the cavity first with the onion quarters then add the fresh sprigs of rosemary and lemon slices. Tie the duck legs with kitchen twine and tuck the wings under the bird.

Transfer the duck onto the rack on the foil-lined sheet pan. Then place in the preheated oven to roast for 1 hour 30 minutes until it registers an internal temperature of 165℉ (about 74℃) on an instant-read meat thermometer. Rotate the pan halfway through cooking. After the 1st hour, loosely cover the duck with aluminum foil so it doesn't over-brown. If you don't have a meat thermometer, make a small cut on a duck breast. If the juices run clear then the duck is ready.

Once the duck is done, remove from the oven and cover with aluminum foil then let it rest covered for 10 to 15 minutes so the juices can redistribute. Cut the butcher's twine and discard. Carve and serve.