Place the squash carefully on a cookie sheet (you want it to stay upright so the butter does not leak out). Bake at 350 degrees for 45 minutes to an hour or longer (until the squash is soft).
Some cooks prefer to steam the squash cut-side-down with a little water or stock first, or to cover the pan, but I prefer to roast the squash this way unless it appears not to be ripe.
You’ll also find fans of honey, nutmeg, allspice, cinnamon and other sweet toppings, but I prefer to keep my squash on the savory side (a touch of soy sauce is OK.)
Don’t throw away the squash seeds. Soak them in warm salted water overnight, remove any stringy pulp and spread the dried seeds on a lightly oiled cookie sheet. Roast the seeds at 300 degrees, stirring occasionally until brown and fragrant, approximately 15 minutes. (Keep a close eye on the seeds as they can go from brown to burnt very quickly.) Taste and add more salt as needed.