Pre-heat your oven to 375°F.
Add a thin layer of your caramelized butter sauce to the bottom. Make sure the sauce coats the entire bottom of the baking pan.
Then place the thin disks of your sweet potato in rows across the entire bottom of the baking pan, layering each disk on top of each other, but only overlapping each disk by half. (Check out my candied sweet potatoes video for an example of this method.)
Drizzle on the caramelized butter sauce in between each layer of sweet potato slices.
Once you are done laying down the layers of sweet potato slices, add a sprinkle of brown sugar and cinnamon on top.
Afterwards, cover with pan with foil and bake for 40-50 mins until the sweet potatoes are fork tender.
Then uncover the pan, place your marshmallows on top, to turn this into candied sweet potatoes with marshmallows!
Afterwards, continue baking for an additional 10 minutes to melt the marshmallows and develop that golden brown crust on top of the sweet potatoes.
Lastly, remove from the oven, and let it sit for about 5 minutes before serving.