It's hard to improve upon the honest goodness of mashed potatoes, but here scallions and brown butter do the trick. The scallions provide sweetness, and the brown butter adds a beguiling nuttiness.
Cooks' note:
Mashed potatoes can be made 1 day ahead and cooled, uncovered, then chilled, covered. (Scallions may discolor slightly when potatoes are made ahead.) Reheat in a microwave or in a heavy pot over moderate heat, stirring.
