HEAT oven to 350°F. Cook 6 marshmallows, butter, cinnamon and salt in medium saucepan on low heat until marshmallows are melted and mixture is blended, stirring frequently. Place in large mixer bowl.
ADD potatoes; beat until blended. Spoon into greased 1-1/2-qt. baking dish; top with remaining marshmallows.
BAKE 15 to 20 min. or until potato mixture is heated through and marshmallows are lightly browned.