Split the squashes in half and scrape out seeds. Line an oven tray with aluminum foil. Season the spaghetti squash with olive oil, salt, garlic powder, and pepper. Place flesh side down and roast for 30 to 40 minutes until fully cooked. Remove from the oven and let rest until cool.
When squash is cool enough to handle, using a large kitchen spoon scrape the strands of squash from the inside of the skin.