Preheat oven to 375F. Arrange potatoes in 13x9x2-inch glass
baking dish. Combine sugar, butter, cinnamon, salt, nutmeg, and
ginger in heavy small saucepan over medium heat. Bring to boil,
stirring until sugar dissolves. Pour over potatoes. toss to coat.
Cover dish tightly with foil.
Bake potatoes 50 minutes. Uncover; bake until potatoes are tender
and syrup thickens slightly, basting occasionally, about 20 minutes.
Increase oven temperature to 500F. Top potatoes with
marshmallows and nuts. Return to oven; bake until marshmallows
begin to melt and nuts begin to brown, about 3 minutes.