Pre-heat the oven to 180°c/Gas Mark 4.
Peel the potatoes and cut into thick slices.
Cook the potatoes in boiling water until just tender. Drain and set aside to cool.
Peel, remove the top and bottom of the onion and finely chop.
Peel and crush the garlic.
Finley chop the mint and coriander.
Make up the stock.
Heat the olive oil in a large frying pan and fry the onion for 2 minutes.
Add the lamb mince and fry for 2 minutes.
Add the garlic, ginger, cinnamon, harissa paste, chopped tomatoes, lamb stock, chopped mint and coriander. Stir well.
Cover, bring to the boil and reduce the heat to simmer for 10 minutes
Line the base of an ovenproof dish with half of the lamb mixture.
Place half of the sliced potatoes on top, repeat.
Add the cream and egg to a bowl and mix. Spoon over the potatoes.
Grate the cheese.
Combine the breadcrumbs, cheese and cinnamon in a bowl and sprinkle over the top of the hot pot.
Bake in the oven for 30 minutes until the topping is brown and crispy.