Make the Salsa Verde up to 2 days in advance. Keep it refrigerated.
Place all pulled lamb ingredients into a casserole with a tight fitting lid and roast, covered for 1 hour at 160°C.
Turn the meat, add more stock if required. Reduce temperature to 140°C and roast further 2 hours until just falling apart.
Rest meat under foil for about 15 minutes. Shred with two forks. It should be so tender that this is no problem.
Boil pasta according to package instructions, slightly al dente is preferred.
Heat oven to 220°C.
Tip drained pasta into a buttered casserole dish and add the shredded lamb and all of the juices from the meat. Stir through.
Add the roasted red onions on top and stir through the grated cheeses and cream. Finish off with some black pepper.
Bake for 20 minutes until top of the dish is sizzling and charring.
Drizzle with the Salsa Verde quite generously and serve with a salad or roasted veggies on the side.
This is the perfect way to use up roast leftovers, so you don't necessarily have to follow all the instructions for the roasting of the lamb.