Heat oven to 200C/180C fan/gas 6. Tip the butternut squash into a non-stick roasting tin and roast for 15-20 mins or until almost soft. Remove and set aside.
Meanwhile, cook the rice following pack instructions until tender. Drain and cover to keep warm. (Set aside the extra for Tuna, sweetcorn and pea wraps, see 'goes well with', if required.) Heat the oil in a wok or large non-stick frying pan over a medium heat. Add the onion and cook for 2 mins until soft but not coloured. Add the ginger, garlic, lemongrass, chilli and spices, and cook for 3 mins more.
Stir through the mango and roasted butternut squash, then add the spinach and pour over the stock and coconut milk. Stir gently to combine, slowly bring to the boil, then reduce to a simmer for a few mins until the spinach starts to wilt.
Add the prawns and stir. Once the prawns are pink through (about 3 mins), remove the lemongrass and discard. Add the tamari, lime juice and coriander, and stir well. Just before serving, check the seasoning, adding more lime juice or tamari if needed. Serve with the rice.