Step 2

Place egg whites, sugar, corn syrup and water in the top of a double boiler. Beat with a handheld electric mixer for about 1 minute.

Step 5

Place pan over boiling water. Make sure the boiling water does not touch the bottom of the top pan. Beat constantly with an electric mixer on high speed for 7-8 minutes, or until it is stiff and glossy. Beat in vanilla and marshmallows. Continue beating until marshmallows are melted and frosting is smooth; about 2 minutes. Use immediately.