Insert a fork or knife under the skin to test that the flesh is tender. When the squash has cooled the skin should peel off easily. Roasting squash helps to maintain squash's delicate flavor. Once roasted and cooled there are a plethora of cooking options available. One option is to mash the squash and use it in any recipe calling for squash puree.
Roasted squash freezes extremely well and reheats easily.
Boiling Method Cut the squash in half and discard the seeds. Then peel and cut the squash into chunks. Place in a saucepan and cover with water. Bring to a boil and cook until the squash chunks are tender. Let the chunks cool, then puree the flesh in a food processor or mash.