In a frying pan, warm the oil and add the onion. Cook for a few minutes until soft then add the cabbage and carrot. Cook for 5 to 8 minutes over medium heat.
Add the lamb and garlic. Mix well and cook gently for another 5 minutes. Add the seasoning, rosemary and stock. Bring to the boil for 5 minutes. Transfer the mixture to two 500ml capacity ovenproof dishes. Arrange the potato slices on top. Cover each pot with foil and place onto a baking tray.
Bake in the preheated oven for approximately 1 hour. Check halfway through to ensure that the hotpots aren't drying out, if needed add a tablespoon more of the lamb stock to each.
After an hour, remove the foil and cook for a further 30 minutes to brown the top or until the potatoes are tender. Remove from the oven and sprinkle with chopped fresh parsley.