Beat together the egg whites, sugar, salt, water, and corn syrup in the top of a double boiler; place over boiling water and continue beating with a rotary beater – electric if you have one – for 4-7 minutes or until the frosting thickens and holds its shape when dropped from the beater. Remove from the stove, add the vanilla, and continue beating until thick enough to spread.
Fluffy Marshmallow Frosting
Beat 1 cup diced marshmallows into the frosting before spreading on the cake.
Put layers together and cover the cake with Seven-Minute frosting. Sprinkle it at once with 1-½ cups shredded coconut.
Instead of the vanilla add a few drops of oil of peppermint to the frosting.
Substitute 1 teaspoon orange extract for 1 teaspoon vanilla.
Substitute 1 teaspoon lemon extract for 1 teaspoon vanilla.