Place lamb shoulder in an ovenproof dish, place 1 sprig rosemary and other herbs on the lamb, and surround with onions and garlic.
Pour the broth into dish (it should cover at least ¾ of the lamb).
Put the lid on and pop in the oven. Reduce the temp to 150C.
Cook for 3 - 4 hours, or until the meat falls off the bone.
Remove from the heat and allow to rest with lid on.
Drain the broth from the lamb into a large fry pan and reduce liquid over a high heat. Use this as gravy for the lamb and veggies.
Set temp to 180C.
Pop the veggies in a large mixing bowl and add the olive oil and seasoning.
Line and baking tray with baking paper. Place the veggies on the baking tray with garlic bulbs and second sprig of rosemary, and spread evenly.
Throw in the oven and cook for 35 - 45 minutes or until veggies are softened and browned (although you get a better result cooking the veg separately on a higher heat, you can put them in the oven at 150C with the lamb, then increase heat to 190C once the lamb is ready for 10 minutes to crisp up the roasted veg).
Remove from the heat and serve with the lamb (pulled lamb meat away from the bone).