Peel and cut the sweet potatoes into half moons, about ½” thick. Place them in a 6 quart slow cooker. Add the sugar, brown sugar, vanilla, cinnamon, nutmeg, cloves and salt and stir to coat the slices well. Slice the butter on top.
In a measuring cup, add the cornstarch to the cold water and whisk until it’s dissolved. Pour into the slow cooker and mix everything well.
Turn the cooker to low and let cook for 3 hours, stirring once or twice during the process. Once the potatoes are tender, turn off and serve while warm.
Notes
* If you wanted to add mini marshmallows to the top to melt before serving you can set oven to low broil and set slow cooker insert inside for a few minutes to brown - insert can be baked up to 400 degrees F, no higher. OR transfer contents to a casserole dish, top with marshmallows and broil this way to brown and melt them before serving.