Boil the sweet potatoes in a large pot until they're fork-tender (15-20 minutes).
Preheat your oven to 350°F (175°C).
Drain the sweet potatoes and mash them until smooth.
Mix in melted butter, milk, brown sugar, maple syrup, vanilla extract, ground cinnamon, ground nutmeg, and salt.
Transfer the sweet potato mixture to a greased baking dish, spreading it evenly.
Generously top with mini marshmallows.
Bake for 25-30 minutes until marshmallows are golden brown.
Allow it to cool for a few minutes before serving.