Place squash, cut sides down, in a baking dish. Pour water into dish around squash halves, about 1cm up the sides.
Bake in the preheated oven until tender and easily pierced with a fork, about 1 1/2 hours. Carefully remove the skin with a fork; it should be very easy to remove. Top squash halves with butter and season with salt and pepper to taste.
To cook a large squash takes 90 minutes. If you have a smaller squash, adjust the baking time.
Try topping with olive oil instead of butter.