Prep: Halve and seed squash. To halve the squash just get in there and cut it in half lengthwise. (Tip: use a small knife and cut all around the squash before using a big knife to cut all the way through). Scrape out the seeds and pulp the same way you would with any squash or a pumpkin.
Bake: Place squash cut side down, rind side up, on a cookie sheet with wax paper or aluminum foil on it. Add a tablespoon of water to the pan. Bake for 40-60 minutes at 375 F or until the squash is easily pierced. Once the squash is cooked, use a fork to scrape the cooked strands from squash top to bottom into a large bowl.
Source: http://www.yourinnerskinny.ca/paleo-spaghetti-squash/