Wash your pumpkin, cut it in half and remove the seeds. If your pumpkin is too large to fit in your slow cooker when it's cut in half, cutting it into quarters works too.
Put enough water in the slow cooker to fill the bottom, and place the pieces of pumpkin inside.
Turn the cooker on low, and cook for 3-5 hours.
Let your pumpkin cool for a bit and then scoop out the pumpkin from the peel. Discard the peel.
Purée with blender or food processor if needed.
Refrigerate or freeze, and use as desired.