Peel and dice yams into large chunks. Place into a 9x13 sized baking dish
Combine brown sugar, butter, cinnamon, salt and nutmeg into a medium saucepan. Over medium heat, bring to a boil stirring constantly until the sugar dissolves
Pour mixture over yams. Stir to evenly coat. Cover with foil and bake for 1 hour
Once yams are tender, pour the marshmallows evenly over top. Turn oven to broil to brown the tops of marshmallows. This should take only a few minutes. Watch carefully