I buy a spaghetti squash at least once a week. This is how I cook it.
I split the squash in half length-wise, scoop out the seeds & pump. I cover each side with aluminum foil and back in the oven for about an hour at 400. I check it by poking it with a fork. Then I scoop it out with a fork and "fluff" it. I use this with sesame shrimp, these AWESOME meatballs that I found a recipe for... I love it!