50g of butter, one small onion (finely chopped), one garlic clove (finely chopped), 180ml of white wine, 170g of mushrooms (roughly chopped), 120g of chestnuts (peeled and cooked, roughly chopped), one tablespoonful of fresh sage (chopped), 100g of fresh breadcrumbs, one egg (beaten), four pork fillets, sea salt, freshly ground black pepper, 140g of streaky bacon, 200ml of crème fraiche.
To make the stuffing, melt half the butter in a pan and slowly soften the onion and garlic over a low heat. Add the mushrooms, turn up the heat to medium and cook for seven to eight minutes. Remove from the heat and stir in the chestnuts, sage and breadcrumbs. Mix in just enough egg to bind the mixture a little (one small egg or about two-thirds of a large one). Leave it to cool. Heat the oven to gas mark 3/170C. Trim any fat from the fillets and slit them lengthways, but not all the way through, so that you can open them out like a book. Season the cut sides with salt and pepper. Spread the mixture over one of the opened-out pieces, then lay the other piece on top, cut side down. Season the top with salt and pepper. Stretch the bacon rashers and wrap them round the meat, tucking in the ends. Tie the fillets with kitchen string in three or four places to secure them. With the bacon ends underneath, put the fillets into a lightly greased roasting-tin, ideally one into which they fit snugly. Season the top with salt and pepper and spread the rest of the butter over the surface, particularly over the exposed bits of pork. Pour the wine around the meat, and roast for 90 minutes, basting frequently and topping up with hot water if it starts to look dry. Remove the meat from the oven, put it on a warm dish and cover it loosely with foil. Add the crème fraiche to the pan, bring it to the boil and cook it until it has thickened slightly. Slice the meat and pour some of the sauce around it. Serve the rest of the sauce separately. This is a rich dish, so keep the accompaniments simple something green and some boiled potatoes, for example.