Preheat the oven to 350°F (175°C).
Boil sweet potatoes until tender, about 20 minutes.
Drain the sweet potatoes and return them to the pot.
Mash the sweet potatoes until smooth.
Stir in maple syrup, brown sugar, melted butter, vanilla, salt, and cinnamon.
Spread the sweet potato mixture into a greased 9x13 inch baking dish.
In a separate bowl, mix chopped pecans and remaining brown sugar.
Top the sweet potato mixture with the pecan mixture and mini marshmallows.
Bake in the preheated oven for 30-40 minutes, until heated through and topping is golden.
Let cool for a few minutes before serving.
