Gather all ingredients and preheat your oven to 350°F (175°C).
Place sweet potatoes in a large pot, cover with water, and boil until tender, about 15–20 minutes. Drain well.
Mash the sweet potatoes with melted butter, salt, and vanilla until smooth and creamy.
Transfer the mash into a greased 9×13″ baking dish, spreading it evenly.
Spoon the mini marshmallows on top in an even layer.
Bake in the preheated oven for 20–25 minutes, or until the marshmallows are golden brown and toasted.
Let it rest for 5 minutes before serving hot.