This squash looks intimidating to cook but it's really simple and the payoff is delicious.
Preheat oven to 400 degrees. With a fork, pierce squash all over. Place on a baking sheet; bake, turning squash once, until easily pierced with the tip of a paring knife, 45 to 60 minutes. (You may also microwave pierced squash on high for 10 to 15 minutes.)
Halve squash crosswise; scoop out seeds. Working over a medium bowl, use a fork to gently scrape flesh in a circular motion to release strands. Add butter; generously season with coarse salt and ground pepper. Toss gently.