Preheat the oven to 120°C (fan) / 140°C (conventional) / gas mark 1.
Place the herbs in the chicken’s cavity and around the chicken in a roasting tray. Add the lemon halves and the garlic bulbs to the tray.
Crush the 2 garlic cloves and add to the butter. Rub the butter into the chicken and drizzle with the olive oil. Season and place in the oven for 3 hrs.
After the chicken has been in the oven for 90 mins, baste with the juices and return to the oven.
About 15 mins before the end of the cooking time for the roast chicken, increase the heat to 200°C (fan) / 220°C (conventional) / gas mark 7 to crisp the skin. Once the skin is crispy, to your liking, leave to rest out of the oven (don’t cover) for about 15 mins.
While the chicken is in the oven, heat the oil in a casserole dish approx 3 litres capacity on a medium heat.
Add the potatoes and cook for about 5 mins. Add the flour and mix, this will help to thicken the gravy for the vegetable casserole.
Then add the vegetables, with the slowest cooking veg going in first, with around 2 minute intervals between each addition (carrots, parsnips, leeks, mushrooms). Hold back on the broccoli for now.
Add the bay leaves, thyme leaves and garlic and mix. Add the wine, if using. Then add the stock and lower the heat and let simmer until the veg is soft.
Season to taste. You can put the lid on the casserole once simmering or if you have cooked the casserole early on and intend to reheat prior to adding the dumplings.
Then make the dumplings. Rub the butter into the flour until it looks like bread crumbs. Add chopped parsley and the Parmesan. Add water and form into a dough. Divide and make 8 balls.
While the casserole is simmering and about 5 mins before increasing the temperature of the oven to crisp the chicken skin, remove the lid of the casserole dish (you will have no further need for it during the remaining cooking steps) and add the broccoli and the dumplings and let the casserole simmer.
Place the casserole dish in the oven with the chicken on 200°C (fan) 15 minutes before the roast chicken has finished cooking. Check in on your dumplings half-way through the cooking time i.e. when you take the chicken out to rest.
Leave the casserole in the oven as the chicken is resting for a further 15 mins (overall about 30 mins in the oven) for the dumplings to turn golden.
Serve the vegetable casserole with the roast chicken and a side of cranberry sauce.