For the turkey ballotine, preheat the oven to 150C/300F/Gas 2.
Lay the bacon out in strips on a sheet of cling film, with the edges overlapping slightly so there are no gaps between each rasher.
Slice the turkey breast crown in half horizontally (but do not slice it all the way through) and open it out like a book. Lay the turkey meat over the bacon layer, cover the top with cling film and beat with a rolling pin or meat mallet until thin. Set aside.
Place the minced veal shoulder in a food processor, add the chopped chicken liver and blend until very smooth. Scrape into a bowl and set aside.
Melt the butter in a pan and stir in the cornflour until well combined and there are no lumps. Gradually whisk in the milk and cook over a medium-low heat for a few minutes, or until thickened to form a roux. Set aside to cool for five minutes.
Pour the milk mixture into the bowl with the minced veal and chicken livers and mix well to combine. Fold in the beaten egg whites, halved pistachio nuts, sea salt, ground white pepper, chopped green pepper, nutmeg and sage leaves. Mix well to combine.
Peel away the cling film from the top of the turkey and spread the mixture in a thick line along the length of the turkey at one end.
Using the cling film as a guide, fold the bacon and turkey over the stuffing and roll up tightly. Remove the cling film and then wrap the turkey roll tightly in two layers of aluminium foil.
Drizzle the olive oil over the base of a roasting tin, add the wrapped turkey ballotine, cover the tin with foil and roast in the oven for 1½-2 hours.
Meanwhile, for the creamed garlic and saffron mashed potatoes, place the potatoes into a pan of lightly salted water and bring to the boil. Reduce the heat and simmer for 20 minutes, or until the potatoes are tender.
Heat the cream and saffron into a small pan and bring to the boil. Remove from the heat immediately and set aside to infuse.
Melt the butter in a pan and add the crushed garlic. Gently fry over a low heat for 3-4 minutes (do not allow the garlic to brown).
Drain the potatoes and return them to the pan over a high heat to drive off any excess moisture. Mash with a potato masher, then mix in the saffron-infused cream and garlic butter. Season, to taste, with salt and freshly ground black pepper.
When the turkey is cooked, remove the foil and pour off the juices from the roasting tin into a small pan. Preheat the grill to high.
Place the ballotine under the grill for 8-10 minutes, turning regularly, until the ballotine is golden-brown all over. Set aside to rest in a warm place.
For the crab apple jelly gravy, reduce the juices from the turkey ballotine over a high heat for 8-10 minutes, or until reduced and thickened. Stir in the crab apple jelly and butter until the sauce is smooth and glossy. Keep warm.
For the roasted beans, preheat the oven to 200C/400F/Gas 6.
Heat the olive oil in a pan and add the lemon zest. Allow to sizzle for about 30 seconds, then remove from the heat and allow to cool. Stir in the herbs and allow to infuse for 30 minutes.
Technique: Zesting citrus fruit Place the green beans into a roasting tray and drizzle over the lemon-infused oil. Season with salt and freshly ground black pepper and toss well to coat the green beans evenly in the oil. Roast in the oven for 10-15 minutes, or until the beans are tender and starting to turn golden-brown.
To serve, reheat the turkey ballotine in the oven briefly if needed, then carve into thick slices. Spoon the mashed potato onto the centre of the serving plates, then top with a slice or two of the turkey ballotine. Scatter the roasted green beans around the edges of the plate, then spoon the gravy over and around.