Using a serrated knife, carefully poke 12-15 holes all around the spaghetti squash. This will prevent it from exploding in your oven while roasting.
Place whole spaghetti squash on a tray or baking dish and roast in the oven for 45 minutes-1 hour. I like to rotate the squash once about half way through the roasting time. The squash is cooked when you can easily pierce it with a fork.
Remove from oven and carefully slice in half lengthwise.
Once cool enough to handle, scoop out the seeds and discard or save for another use.
Use a fork to shred the inside of the squash to spaghetti like strands.
Store the "spaghetti" in refrigerator if not using right away.