Wash the skin of the butternut squash thoroughly, and cut it in half lengthwise. Remove the seeds and pulp with a spoon. Rub both sides of the two halves with a little oil, and sprinkle with salt and pepper. Roast at 190°C (Gas Mark 5 / 375°F), skin side down, for around an hour, or until the flesh is fairly soft.
While the squash is roasting, heat 1tbsp of oil in a frying pan, and add the garlic, paneer, spring onions, tomatoes and spices. Cook over a medium heat for 5 minutes, until the tomatoes have cooked down and the mixture is fragrant. Add a few tbsp of fresh coriander, and set aside.
When the squash is ready, scoop out a small amount of the flesh from the area around where the seeds were, and add it to the paneer mixture. Mix well, and spoon the stuffing back into the squash halves. Return to the oven for a further 15 minutes.
Add the 1/4 tsp of cumin and 1/4 tsp of ground coriander to the yogurt, and mix well.
When the stuffed squash is ready, serve it topped with the spiced yogurt and more fresh coriander. The skin is perfectly edible, but you might want to just scoop out the flesh if it feels a bit tough.