Start by preheating your oven to 160°C (320°F). Drizzle olive oil in a large roasting tray. Put the lamb shoulder in the center and drizzle it with a bit more olive oil. Season generously with salt and pepper. This little ritual infuses the meat with flavor and ensures it comes out succulent. Roast for about three hours. Your kitchen will smell heavenly.

While your lamb is roasting, chop the carrots, swede, celery, and onions. The key here is uniformity in size. It ensures even cooking. Once done, put them aside. Cut the roasting time down by preparing them actively.

After the lamb is done and the juices are gloriously released and luscious, remove it from the tray and set it aside to cool. Add your chopped vegetables into that same tray. Cook them over medium heat for about 8 to 10 minutes. Stir them occasionally until they begin to caramelize slightly.

Once the lamb is cool enough to handle, carefully shred it using forks. Don’t throw away the bone. It’ll add more depth to your filling. Stir the shredded meat back into the vegetable mix. This fusion is where the magic happens. Add a splash of water if needed, and let it simmer for another 10 minutes. The flavors meld together so beautifully.

While your filling is simmering, boil the potatoes in salted water. Once fork-tender, drain them and return them to the pot. Add the butter, milk, salt, and pepper. Mash until creamy. A good mash is essential.

Now for the fun part! Preheat your oven to 200°C (400°F). Spoon the meat and vegetable mixture into a deep baking dish. Spread the mashed potatoes over the top. Use a fork to create peaks and valleys. This gives texture, which leads to a delightful crunch.

Place the assembled pie in the oven for around 30 minutes. You want the top to be golden-brown and bubbling. The anticipation will increase with each minute!