Preheat oven to 425 degrees.
Rinse and peel potatoes. Slice into rounds. You can slice as thick or thin as desired, but remember that thick rounds will need a bit longer to bake. Tip: slice about ¼-1/2 inch wide.
Lay the sweet potatoes into your baking dish. Slide the rounds apart a bit so they have some room to breathe.
Pour the optional citrus juice over top the potatoes. Optional: zest some of the citrus peel over top for extra citrus flavor.
Sprinkle the cinnamon and coconut sugar over top the potatoes.
Slice up the butter and add in pieces over top the potatoes.
Add 2-3 marshmallows to the pan. Stuff then under and in between the potatoes so they are not right on top. Cover with foil.
Bake at 425, covered, for 35 minutes. Then remove the foil and add the remaining marshmallows over top. Bake for an additional 5-10 minutes to melt and brown marshmallows.
Serve warm.