4 small (480g) potatoes, quartered
1/4 cup (60ml) olive oil
2 cloves garlic, crushed
1 small (200g) leek, sliced
4 slices (45g) pancetta, chopped
1/2 cup (60g) coarsely grated matured cheddar cheese a/4 cup (40g) chopped raisins
Boil, steam or microwave potatoes until tender; drain. Place potato in small bowl; mash until smooth.
Heat 1 tablespoon of the oilin medium pan; cook garlic and leek, stirring, until soft. Remove from heat, stir in potato, pancetta, cheese and raisins. [Can be made ahead to this stage. Cover; refrigerate overnight or freeze.]
Spread a quarter of the potato seasoning inside boned cavity of lamb; spread another quarter of the seasoning along centre of lamb. Roll from short side to enclose seasoning; secure lamb with skewers, tie with kitchen string at 2cm intervals. Shape any remaining seasoning into a log; wrap in oiled foil, twist ends to secure. Place lamb on wire rack in large baking dish, brush with remaining oil.
Bake, uncovered, in moderate oven 1 hour. Place seasoning log on wire rack with lamb; cook lamb, uncovered, another 30 minutes. Cover lamb loosely with foil; stand 20 minutes before carving.