Preheat the oven to 240°C/220°C fan and line a roasting tin with baking paper.
Put the butternut squash into the lined roasting tin, toss with 1 teaspoon of olive oil and a pinch of salt, spread out evenly. Roast for 25-30 minutes until tender - a knife should slide through easily.
Heat 1 teaspoon of olive oil in a large, heavy-based pan over a medium heat. Add the onion, ginger, garlic and half a teaspoon of salt and cook gently for 7-8 minutes until the onion is softened and translucent.
Stir in the cumin, paprika, curry powder and turmeric with a splash of coconut milk to loosen into a thick paste. Cook for 2-3 minutes, stirring often, until fragrant.
Add the remaining coconut milk, passata, chickpeas, cashews and roasted squash. Stir well and simmer gently for 5 minutes. Remove from the heat and season further with salt, if needed (remember the halloumi will add seasoning, too, as it's salty).
Meanwhile, heat the remaining 1 teaspoon of olive oil in a non-stick frying pan over a medium-high heat. Add the halloumi slices and fry for 1-2 minutes on each side until golden.
Spoon the curry into bowls and top with the halloumi and fresh coriander.
