Add the peeled and diced sweet potatoes to the slow cooker. Slice the butter and place on top. Pour over the water.
Cover and cook on HIGH for 4 hours without opening the lid during the cooking time.
When the cooking time is done, add the maple syrup, heavy cream, cinnamon, nutmeg and salt. Using an electric mixer, beat until smooth OR use a potato masher and mash by hand.
Serve with additional butter if desired.
Enjoy!
Video
Notes
Store any remaining sweet potatoes in an airtight container and keep in the fridge for up to 4 days.
The next best (and easiest appliance) to use instead of a masher would be an electric hand mixer (or stand electric mixer). Either one will work fine.
You can keep these potatoes on warm for a few hours. You may need to add a splash of water to keep them moist; be sure to stir occasionally.