There’s more than one way to cook a winter squash…but I still find baking the easiest and most reliable method. This advice is to folks just gearing up with their winter squash exploits: carefully (yes, I know they are all hard, so be aware of where your fingers are) cut your squash in half and scoop out the seeds. If you are cutting a butternut in half, you need to do it lengthwise because the seeds are only in the bottom bulbous part. Place cut side down on a lightly greased baking sheet and bake at 350 until easily pierced with a fork (20-45 minutes, depending on size and variety). You can bake a winter squash whole, but pierce the skin all over, as once in a rare while the squash will explode all over your oven. Once cooked, you can scoop out the squash and use in any recipe calling for mashed squash. I have been known to microwave the small squashes, like Delicata or Sweet Dumpling, for a few minutes, until they feel like a baked potato, then cut open, scoop out seeds (HOT) and eat out of the shell/skin. Again, be sure to pierce the skin before cooking.
When I bake squash, I tend to do more than I need, freezing the leftovers. I generally measure the mashed squash into containers or bags, mark the amount on the bag, toss in the freezer, and then it is ready to go for muffins, cheesecake, leftovers…
If you are feeling very industrious, or have dwarves around (On Golden Pond reference), pick through the seeds, removing strings and bits, spread out on a greased baking sheet, lightly salt, and bake at 350 for about 10 minutes (until golden brown) You can even do this in your toaster oven. These are a great snack and are also perfect for garnishing your squash soup!
*Worst way someone ever advised me to cook a butternut: boil the whole thing in a pot of water until done. Yeah, ’cause I was going to catchup on ironing the underpants, and de-frosting the downstairs freezer!