Tip the rice into a large bowl, then add 500ml of the hot vegetable stock. Cover with cling film and microwave on High for 5 mins. Meanwhile, peel and cut the squash into medium chunks (see tip, below). Stir the rice, then add the squash and the rest of the stock. Re-cover with cling film, then microwave for another 15 mins, stirring halfway, until almost all the stock is absorbed and the rice and squash are tender.