Place the cubed sweet potatoes in a large pot and cover with water. Bring to a boil and cook for about 15-20 minutes, until they are tender.
Drain the sweet potatoes and transfer them to a large mixing bowl. Mash them until smooth.
Add the brown sugar, maple syrup, melted butter, vanilla extract, cinnamon, nutmeg, and salt to the mashed sweet potatoes. Mix well until all ingredients are fully combined.
Transfer the sweet potato mixture to a greased 9x13-inch baking dish, spreading it evenly.
Sprinkle the mini marshmallows evenly over the top of the sweet potato mixture.
If using, sprinkle chopped pecans over the marshmallows for added crunch and flavor.
Bake in the preheated oven for 25-30 minutes, or until the marshmallows are golden brown and slightly toasted.
Remove from the oven and let cool for a few minutes before serving.
Notes
Serve warm, garnished with cinnamon and extra pecans for a festive touch.