Begin by positioning the oven rack in the center and preheat your oven to 400°F. Line a baking sheet with parchment paper for easy cleanup. Stabilize the spaghetti squash by placing a dish towel under it on your cutting board, then trim about 1/4 inch from both ends of the squash.

With the squash standing upright, carefully slice it lengthwise from top to bottom. Use a sturdy spoon to scoop out the seeds from the center cavity; these can be set aside for roasting later if desired.

Brush the inside of both squash halves with olive oil, and evenly sprinkle salt over them. Place the squash halves cut side down on the prepared baking sheet. Roast for 30 to 45 minutes, or until the skin is easily pierced with a fork.

Once roasted, allow the squash to cool slightly until it can be handled comfortably. Using a fork, scrape the inside of the squash, pulling in one direction to create spaghetti-like strands.

Finish by tossing the strands with butter for added flavor, and serve warm.