2) Add the apples, prunes and half the chopped rosemary. Cook the apples, stirring occasionally, until they start to soften, about 5 minutes. Pull the pan off the heat and add the brandy. Return to the fire and flambé, or let the alcohol just burn off. Remove from the heat and allow to cool.
3) Lay out a length of cling film about 60cm long. Spoon the apple mixture onto the cling film and make a log down the centre that is about the same length as the pork loin. Roll the cling film tightly around the apple mixture and twist at the ends to secure. The log should be about 2.5cm in diameter. Place the log in the freezer and let it freeze solid. This can and should be done ahead of time.
To stuff the pork:
1) Insert a long, thin knife into the centre of one end of the pork loin; repeat this process at the other end. Wiggle the knife back and forth to create a place big enough to accommodate your frozen stuffing log. After cutting with the knife, you can use the handle of a long wooden spoon to make sure the incision goes all the way through the pork loin.
2) Preheat the oven to 190C/Gas 5. Take the stuffing log from the freezer and remove the cling film. Slide the stuffing log through the pork loin; it might need a little encouragement but it should go the length of the loin. Season the outside of the pork generously with salt and sprinkle it with the remaining chopped rosemary.
3) Coat a roasting tin with olive oil and bring to a high heat. Add the pork to the roasting tin and sear it on all sides until it is brown.
4) Remove the pork to a plate and pour off the fat in the roasting tin. Add the pork back to the tin and pour in the chicken stock. Place the pork in the oven for 25 to 35 minutes, depending on how done you like it; for pink meat remove it from the oven when a meat thermometer reaches 54C. Turn it over halfway through the cooking time.
5) Remove the pork from the oven, tent it with foil and leave it rest for 15 minutes before carving.