I have 2 ways of cooking this. It is one of our favorite vegetables.
Cut squash in half length wise and scoop out seeds (like a pumpkin).
Place halves , cut side up, in baking dish. Sprinkle with salt and pepper. Dot with margarine or butter. (Especially get it into the depression where the seeds were. Pour water into dish until 1/4 in. deep. Cover and bake 400 deg oven 30-40 min. 350 deg oven 40 min. or 325 deg oven for 45 min.
Pierce squash several times with knife and microwave for 4-6 minutes. Cool slightly. Cut in half and remove seeds. Arrange halves cut side down on plate. Cover and microwave 5-8 minutes or until squash is tender.
After the squash is cooked scoop out insides from rind. Insides should be fork tender and mashable. Add salt pepper, and lots of butter. Mash. I sometimes use brown sugar instead of salt and pepper.
If squash is not tender enough stick back into microwave until tender.