Preheat oven to 400 degrees F (204 C) and line a large rimmed baking sheet or baking dish with parchment paper or foil.
Carefully halve spaghetti squash lengthwise using a sharp knife. I find the best way to do this is inserting the very tip of a very sharp large knife into the side of the squash (lengthwise) and push it all the way through to the other side. Then rock the knife back and forth to cut one half all the way through, then repeat on the other side.
Use an ice cream scoop (or sharp spoon) to scrape out the seeds and most of the stringy parts.
Brush the interior with oil and sprinkle with a little salt. Place cut-side down on baking sheet. Roast for 45 minutes, or until a knife easily pierces the skin and flesh. Remove from oven and set aside.
Note: For a more moist squash, omit the oil and instead add just enough water to cover the bottom of your baking sheet or baking dish and bake at 400 degrees F (204 C) until a knife easily pierces the exterior - about 35-45 minutes.
Once slightly cool, flip squash flesh-side up and use a fork to scrape out the strings. For ideas on how to use your spaghetti squash, see the text links above!
*Nutrition information is a rough estimate for a squash yielding ~4 cups calculated with oil and salt, and without additional toppings / garnishes.