Peel sweet potatoes. Using a mandolin, carefully slice the potatoes lengthwise (the long side). Place the slices in a medium-sized bowl and add sugar. Let them sit for 1 hour or refrigerate overnight.
For a perfect circle, start with one slice, roll it up like a ribbon, and keep adding slices until you reach the desired size. For a faster method, stack 4-5 slices and roll them together. Secure with twine.
In a cast-iron skillet or Dutch oven, melt 2 tbsp butter, 1 tbsp ghee (or other oil), 1-2 tbsp brown sugar, cinnamon, nutmeg, and other spices.
Place the rolls in the skillet and drizzle with 2 tbsp melted butter + 2 tbsp brown sugar (more if needed). Bake at 450°F for 20 minutes, flip the rolls, and bake for another 20-30 minutes. If the tops are not browned, broil for 4 minutes.
Serve with crushed pecans and maple crème, or top with marshmallows and broil for only 1 minute (they burn quickly).