1-First, preheat the oven to 160˚C (140˚C fan-forced). Coat the lamb shanks in seasoned flour by placing the flour and seasoning in a large bag and shaking with the lamb to coat, then shake off excess. Brown the lamb shanks in 1 tablespoon of olive oil in a large ovenproof pan over medium-high heat and set aside.

2-In the same pan, heat the remaining oil and cook the onion, garlic, celery, carrots, mushrooms, and rosemary for 3-4 minutes until softened. Stir in tomato paste and cook for 1 minute. Add beef stock and diced tomatoes, bring to a boil, cover, then return the lamb shanks to the pan, cover, and bake for 2 to 2½ hours until the lamb is tender and the sauce thickens.

3-Remove the lamb shanks, cool slightly, then remove and chop the meat, returning it to the mushroom mixture. Spoon the mixture into four greased ovenproof dishes (each about 1½ cups). Increase the oven temperature to 190°C fan-forced. Defrost the pastry sheets, cut four 11 cm rounds, place them on the pies, seal edges with a fork, brush with beaten egg, and cut a small cross in the center to allow steam to escape.

4-Place pies on a lined baking tray and bake for 25-30 minutes until the pastry is puffed and golden. Serve warm.