Preheat the oven to 400°F. Lightly grease a baking sheet with no-taste oil.
Set the squash on a cutting board. Lift a cleaver or other heavy knife high in the air with both hands and do a walloping karate chop down the center of the squash, or as close to the center as you can get. If the halves are very large, and seem like they will take a long time to cook through, cut them in half again, like I did. If you’re using a butternut, just cut off the round bottom from the long neck, and then cut both pieces in half down the middle. The most important thing is to keep your fingers far away from where the blade of the knife comes down.
Scoop out the squash seeds. If they’re good for eating, like butternut squash seeds, clean them off and roast them separately.
Place the squash flesh side down on the baking sheet. Bake for 45 minutes. At this point, the skin should be soft enough that you can poke several holes in it with a fork, which will help it to cook the rest of the way. Continue roasting for another 15 minutes, or until the flesh is very tender.
Let the squash cool to room temperature.
Scoop out the flesh. Discard the skin.
Cook the squash into your favorite dish. If you’re using the cooked squash to make pumpkin pie, you can put it in a food processor and whiz it around several times to make the flesh very smooth and creamy.