Spray 6 qt slow cooker with cooking spray.
Prick the outer layer of the spaghetti squash on all sides, about 10 times total.
Pour 1/2 cup water into slow cooker and place spaghetti squash inside. Close lid and turn on low.
Cook 4-6 hours on low (2-3 hours on high), until spaghetti squash is soft to the touch. Once cooked, pull out and let sit and cool for 10 minutes before cutting in half and scooping out the seeds with a spoon.
Use a fork to separate the "noodles". Serve immediately. Refrigerate any leftovers for up to one week.