Preheat the oven to 350°F (175°C).
Peel and boil the sweet potatoes until fork-tender.
Drain the potatoes and mash them in a large bowl.
Mix in sugar, milk, melted butter, eggs, vanilla, and salt until well combined.
Pour the mixture into a greased baking dish.
Bake the casserole for 25 minutes.
Top with mini marshmallows and pecans.
Return to the oven and bake for an additional 10-15 minutes until golden.
Let the casserole cool slightly before serving.