It could be Marshmallow, 7 minute or White Mountain frosting. They are all
pretty close in flavor and texture. This is the one that I prefer.

Marshmallow Frosting:

PLace in top of double boiler........
2 egg whites
1/2 c. white corn syrup
1/2 c. sugar
1/8 t. salt
Beat until partially mixed.Place over rapidly boiling and beating
constantly until frosting stands in peaks, 3 to 4 minutes.

Add and continue beating until melted ..............
3/4 c. fresh mini marshmallows or 1/2 c. marshmallow creme
Remove from heat and continue beating about 1 minute.
Add...............
1 t. vanilla
Beat well and frost.