Preheat your oven to 400°F (200°C).

Wash and dry the potatoes thoroughly.

Cut slits into each potato without going all the way through.

Rub the lamb shoulder generously with olive oil, salt, pepper, minced garlic, and chopped rosemary.

Let the lamb sit at room temperature while prepping the potatoes.

Place the Hasselback potatoes in a baking dish and drizzle with olive oil.

Sprinkle salt and pepper liberally on the potatoes.

In a large roasting pan, place the seasoned lamb shoulder in the center.

Arrange the potatoes around the lamb.

Squeeze fresh lemon juice over both the lamb and potatoes.

Roast everything for about 1 hour 30 minutes or until the internal temperature of the lamb reaches 145°F (63°C).

Halfway through cooking, baste both the lamb and potatoes with pan juices.

Let the lamb rest for 10 minutes before slicing.