It takes around 35 to 50 minutes to cook spaghetti squash in the oven at 400 F.
To cook the spaghetti squash in your oven preheat the oven to 400 F and while the oven is preheating to 400 F prepare the spaghetti squash by slicing the squash in halves.
Scoop the seeds out of the spaghetti squash and then place the halves of the squash with the slices facing down on a roasting pan.
Pour enough water into the bottom of the roasting pan to cover the bottom of the squash and then bake the spaghetti squash for 30 to 50 minutes.
The spaghetti squash will be fully done when it's tender and can be easily pierced with a fork.