1. Coat the lamb shanks lightly with flour and shake of the excess.
2. Heat oil in a large frying pan over high heat. Add the shanks and cook for about 2 minutes each side or until nicely browned.
3. Remove and set aside.
4. Add the onion, garlic and leek to the pan and cook for 3 minutes or until soft.
5. Once cooked, add the stock, wine, carrots, parsnips, rosemary, garlic, onion and leek to the slow cooker.
6. Add your shanks and season with salt and pepper.
7. Cook on low heat for at least 8 hours.
8. Once cooked, remove the shanks from the cooker.
9. Use a ladle to remove sauce (including vegetables) from the cooker and add to a saucepan.
10. Mix together the cornflour and water to form a paste.
11. Preheat oven to 180 degrees.
12. With the saucepan of sauce on medium heat, gradually pour in the paste. Allow the sauce to thicken and when it is of a consistency that you like, you can remove it.
13. Place a lamb shank in each pie dish. Cover the shank and fill the rest of the dish with sauce. Cover with pasty.
14. Place pies in oven and cook until pastry has browned.