1.Preheat oven to 200°C/400°F.
2.Remove and discard bread crusts; cut bread into 1cm (½-inch) cubes. Heat half the oil in large frying pan; cook bread, stirring, until browned and crisp. Remove croûtons from pan.
3.Heat remaining oil in same pan; cook onion, garlic and pancetta until onion browns lightly. Stir in spinach; remove from heat. Gently stir in croûtons, nuts and stock.
4.Place pork on board, fat-side down. Horizontally slice through thick part of pork, without cutting whole way through. Open out pork to form one long, fairly flat piece; press stuffing mixture along short end of pork. Roll pork to enclose stuffing, securing with kitchen string at 2cm (¾-inch) intervals.
5.Place rolled pork on wire rack in large shallow baking dish. Roast, uncovered, about 1¼ hours or until cooked through.
6.Meanwhile, make plum and red wine sauce. Bring ingredients to the boil in small saucepan. Reduce heat; simmer, uncovered, 10 minutes or until sauce thickens slightly.
7.Serve sliced pork with sauce and steamed asparagus, if you like.
When you order the pork loin, ask your butcher to leave a flap measuring about 20cm (8 inches) in length to help make rolling the stuffed loin easier.Note