Gather all ingredients. Preheat the oven to 400 degrees F (200 degrees C).
Place drained sweet potatoes in a medium baking dish. Distribute butter pieces evenly over the sweet potatoes.
Sprinkle with brown sugar. Layer with miniature marshmallows.
Bake in the preheated oven until sweet potatoes are tender and marshmallows have melted, about 20 to 25 minutes.
Enjoy!
Notes
Cook’s Note
This is one of those easy holiday casserole side dish recipes that you can toss together a day or two ahead of time (hold aside the marshmallows so they don't dissolve as they sit), cover, and keep in the fridge until you're ready to top with marshmallows and bake.