Preheat the oven to 200°C/400°F. Place the butternut squash on a large, rimmed baking sheet. Drizzle over the olive oil and season with salt. Place in the oven and roast for 25-30 minutes until just cooked and starting to caramelize.
To make the curry sauce, soften the onion in a little oil or butter in a large pot. Add the garlic and ginger and cook until fragrant. Add the spices and fry for 30 seconds then pour in the tomatoes, sugar, stock and coconut milk. Season to taste then allow to simmer for 15-20 minutes until the sauce has thickened and reduced slightly.
Add the roasted butternut to the curry sauce and allow to cook for another 10-20 minutes or until the butternut is cooked.
To make the chickpeas, heat the oil in a large frying pan then add the drained chickpeas. Fry until the chickpeas start to brown then add the spices. Cook until the chickpeas are crisp and golden then remove from the heat.
Serve the butternut curry over rice topped with the crispy chickpeas.