Start this recipe by preparing the pork. Cut the pork open into a large thin layer able to be stuffed. Next, lay a large piece of cling film onto your work surface and cover with the sliced pancetta. Next, spread lightly with 2 tbsp cranberry jam and lay the pork fillet on top. Next, make the filling by frying together the onion, garlic and fresh herbs with the butter and oil for 10 minutes till soft. Stir in the stock pot and season well with salt and pepper and remove off the heat. Stir in the nuts, cranberries and beaten egg, followed by the breadcrumbs to make the stuffing. Use the mixture to stuff the pork fillet and roll up tightly using the cling film for support. Tie up the ends and place into the fridge to chill for an hour and firm up. When ready, remove from the cling film and sear on all sides in a pan with hot butter. Transfer to a baking tray and cook for 20-22 minutes or until cooked through. Use any juice to make a gravy and add in the last tbsp cranberry jam for extra flavour. Serve the gravy on the side with roasted vegetables and potatoes and the stuffed pork fillet cut into thick slices.