Pumpkin and sage stuffing
Preheat the oven to 150°C and line a baking tray with tinfoil.
Coat the onion squash or pumpkin with the sunflower oil, all spice and salt then roast in the oven for one hour.
Scrape out the pumpkin or onion squash flesh, leave to hang in a muslin cloth to remove any excess juice.
In a pan, sweat the shallots, garlic, sage and salt for roughly 10 minutes.
On a separate baking tray, dry roast the pumpkin seeds with salt for 10 minutes or until golden brown and crunchy.
In a bowl, combine the pumpkin or onion squash, shallots mix and seeds with the chestnuts, breadcrumbs and sherry vinegar and mix together.
Stout onion jus
Increase the oven to 170°C.
Wash and peel the vegetables, then dice into 2-inch cubes, leaving the garlic whole. On a lined baking tray, coat the vegetables in 50 ml of sunflower oil and cook for one hour.
Cut the mushrooms into quarters then add to a pan. Cook in 40 ml of sunflower oil on a high heat to achieve colour. Add the water and bring to the boil. Leave to infuse.
Once the vegetables are coloured, drain the excess sunflower oil. Place back into the pan, add the stout and reduce by 75%.
Add the mushroom stock and the pre-roasted garlic. Bring to a simmer, remove any scum or oil that forms on top of the stock throughout the simmering stage. Simmer for 20 minutes, then pass through a sieve into a measuring jug.
Pour the liquid into a pan and reduce.
Combine the corn flour with an additional teaspoon of water and mix to a paste, then whisk into the boiling sauce until it reaches the desired thick consistency.
In a pan add the sugar and water then bring to the boil. Stir in the cranberries and simmer for five minutes until tender but holding their shape. Leave to cool.
Brussels sprouts and Romanesco cauliflower
Reduce the oven to 160°C.
Cut the sprouts in half and boil in salted water for one minute then refresh in ice water, dry and set aside.
Cut the Romanesco into small pieces and cook in boiling water for three minutes then refresh in ice water.
Coat the sprout halves in sunflower oil, salt and pepper and place in the oven for 3 - 4 minutes until tender and golden.
Leaving the skin on, cut shallots into 1/3rds. Add the sunflower oil to an oven-safe pan and cook the shallots until they begin to colour. Put the pan in the oven for 10 - 15 minutes, until the shallots are tender.
In a bowl, mix all the ingredients together.
Peel and wash the celeriac, cut two 1.5-inch slices. In a pan, seal in sunflower oil on a low-medium heat.
Once the celeriac slices have coloured slightly, insert the cloves. Place the pan in the oven preheated at 160°C and cook until tender. Once cooked, allow to cool and remove the cloves.
Crispy Marmite potatoes
Increase the oven to 180°C.
Wash and peel the potatoes, then using a Parisienne scoop, scoop balls out of the potatoes. Place in water and set aside.
Parboil the potatoes in water for five minutes, or until softened. Dry, then place the potatoes on a lined baking tray. Coat with sunflower oil and cook in the oven until crispy and golden brown.
Once the potatoes are golden, add the marmite and mix well. Add the breadcrumbs, then cook in oven until crispy. To finish, add parsley.
Arrange each of the celeriac slices in the centre of the plate. Serve with the potatoes, roasted sprouts, stuffing and cranberry sauce. Pour over the onion jus and grate some truffle over the dish.