Preheat over to 400F. Cut the squash in half, lengthwise, from stem to end with a strong knife. Scoop out the seeds and stringy stuff. Score the insides several times with a knife. Place each half in a baking dish cut side up. Add about 1/4 inch of water to the baking pan. Coat insides with a little butter and salt. You may also add a bit of brown sugar or maple syrup. Bake for 1 hour or a little longer, until soft. Serve hot.
Mashed or Soup:
Prepare in same way as above, except cook squash cut side down. Obviously, you do not fill it with anything. When done, remove from oven and use a silicone baking glove to hold hot squash half while scooping out the insides into a bowl. Add butter and salt to taste. Stir vigorously until creamed. May add a teaspoon or so of heated heavy cream.
This is also the beginning steps to a great soup. Just scoop the squash into a saucepan instead of a serving bowl. Add 1 part chicken broth and one part milk until desired constancy. Add salt and butter to taste. Heat through and serve immediately.