How to Make It
Preheat the oven to 425°. Prick the sweet potatoes all over with a fork and place on a baking sheet. Bake for 45 minutes, until tender when pierced; let cool slightly. Halve the sweet potatoes and scoop the flesh into a large bowl. Add the milk, butter and brown sugar and coarsely mash. Season the sweet potatoes with salt and black pepper and spread them in a 9-by-13-inch baking dish. Lower the oven temperature to 350°.
In a medium bowl, toss the marshmallows with the five-spice powder until coated. Scatter the marshmallows over the sweet potatoes and bake for about 45 minutes, until the sweet potatoes are hot and the marshmallows are golden and lightly puffed.