Preheat the oven to 200°C.
Cut the squash in half and scoop out the seeds. Put the squash cut-side down in a baking dish and bake for 35 – 40 minutes, until tender.
Meanwhile, heat the oil in a frying pan over medium heat. Cook the minced lamb with the cinnamon, cumin and about 1 teaspoon of salt until it changes colour. Add the harissa paste and tomato purée and stir for 1 minute.
Remove the lamb with a slotted spoon, leaving the cooking jus in the pan. Set it aside.
Add the onion to the pan, and cook gently for 5 minutes. Add the garlic and stir for about 30 seconds. Stir in the bulgar wheat or rice and the water. Cover, reduce the heat and simmer for about 10-20 minutes, until tender. Rest for 5 minutes.
Return the lamb to the pan, add the raisins, parsley and pine nuts. Mix well.
When the squash is cooked, remove from the oven and scoop out most of the flesh. Mash this with a fork into coarse bits and combine with lamb mixture. Taste and season with salt an pepper to your liking.
Stuff the squash shells and bake for about 15 minutes until golden.