For the casserole, place the venison into a bowl with the red wine, port, thyme, garlic, bay leaf, peppercorns and juniper berries, stir well then leave to marinate in the fridge overnight.
Preheat the oven to 140C/275F/Gas 1.Remove the venison from the bowl, reserving the marinade, and dry with kitchen paper.
Heat a heavy-based ovenproof casserole pan until hot, add the oil then the venison and brown the meat on all sides over a high heat. Remove the meat from the pan and set aside.
Add the bacon and vegetables to the pan, along with a pinch of salt, and cook until the vegetables are lightly browned.
Add the reserved marinade, cook until it has reduced by two-thirds then place the venison back in the pan, add the stock and bring to a simmer.
Cut a piece of greaseproof paper to the same size as the top of the pan and place on top of the casserole.
Place the pan in the oven and cook for 2-3 hours until the meat is tender. Allow the casserole to cool, then remove the venison shanks and set them aside.
Sieve the cooking juices then return them to the pan and reduce by at least a half or until the sauce is rich and dark. Set the pan aside until ready to finish.
For the roasted vegetables, turn the oven up to 170C/325F/Gas 3.
Wrap the squash and beetroot in a foil parcel with the salt, thyme, garlic and vinaigrette and a couple of tablespoons of water. Place on a baking tray in the oven and bake for 30-40 minutes until tender.
Meanwhile, cut the pears in half, remove the cores and season with salt and freshly ground black pepper.
In a large pan, warm half the butter and then add the pears cut side down. Allow the butter to get very hot and turn a light brown colour, then turn the heat down and cook gently for 8-10 minutes until the pears are tender.
Add the chicken stock, let it bubble then remove the pears from the pan and set aside in a warm place.
Blanch the parsnips in boiling water then transfer them to the same pan you used to cook the pears and add the remaining butter. Cook gently until the parsnips are tender and golden-brown.
To finish the casserole, return the venison shanks to the pan, add the chestnuts and gently warm through.
Serve the casserole on warmed plates with the squash, beetroot, pears and parsnips alongside.