Prepare the duck as per roasting instructions on-pack. Place the duck on a trivet in a baking tray big enough to allow you to fit the potatoes around the duck and add the duck fat.
Place the duck into the oven. After 45 minutes, place the potatoes in the tray, baste with the duck fat and add the rosemary, onion and garlic. Season with a generous amount of salt and place back in the oven. Every half an hour, turn and baste the potatoes with the duck fat.
When the duck is ready as per cooking instructions on-pack, remove from the oven and keep warm. Remove the potatoes, baste with more duck fat and place back in the oven until cooked.
Carefully pour off any remaining fat from the liquid in the baking tray into a heat-proof bowl and save for another time. You should be left with just the juices, garlic, rosemary and onion. Add in the wine, bring to the boil and scrape the bits off the bottom of the tray. Strain into another pan, add the chicken stock, and reduce by half or until it starts to thicken. Stir in the butter and honey. Taste for seasoning and sweetness, adjust accordingly and serve.