Preheat your oven to 350 °F (175 °C).
Boil the sweet potatoes in salted water for about 15 minutes or until tender. Drain and mash.
Combine mashed potatoes with melted butter, brown sugar, milk, eggs, vanilla, cinnamon, nutmeg, and salt. Mix until smooth.
Pour mixture into a greased 9×13 baking dish and spread evenly.
Top with mini marshmallows. For extra crunch, sprinkle pecans before adding marshmallows.
Bake for 25–30 minutes until the marshmallows are golden and puffed.
Cool slightly before serving warm.
