Preheat oven to 375 degrees F.

Cut six 2-foot lengths of butcher's twine. In a small skillet saute apple and shallots in butter 1 minute or until lightly browned. Transfer to a small bowl and mix well with goat cheese, pine nuts and mint; season to taste with salt and pepper. Arrange lamb on work surface, inside facing up. Place a sheet of plastic wrap over lamb and pound with a meat mallet to flatten meat slightly, if needed, until leg is a fairly even thickness. Remove plastic wrap and generously season inside and outside of lamb. Mound stuffing mixture lengthwise along one side of lamb; roll up lamb over stuffing, tucking in ends. Space 5 pieces of twine under lamb roll and tie them firmly, starting at outside and working in. Tie roll lengthwise with remaining piece of twine.

In a roasting pan set over 2 burners, heat oil over high heat. Add lamb roll and sear all over, about 6 minutes in all. Transfer lamb to a rack and set down in the roasting pan. Roast until brown and tender and an instant read thermometer reads 140 degreees F for medium rare, about 1 hour to 1 hour and 15 minutes, basting occasionally. Remove from oven and let sit, covered loosely with foil, 10 minutes. To serve, discard strings, slice in 12 pieces and serve 2 slices per serving with roasted rosemary potatoes