Marshmallow Icing

This old-school frosting starts with a cooked sugar syrup poured into stiffly beaten egg white, similar to a classic seven-minute icing but with diced marshmallows folded in. The marshmallows melt from the heat of the syrup and give the finished icing a softer, more stable texture that holds its shape on a cake without weeping.

Getting the sugar syrup to soft ball stage (236°F / 113°C) is the one step you can’t fake. Too cool and the icing stays runny. Too hot and it turns grainy and stiff. A candy thermometer takes the guesswork out entirely.

Cream of tartar in the syrup prevents the sugar from crystallizing as it boils, which is what keeps the final icing silky instead of gritty. It’s a tiny amount but makes a real difference in the finished texture.

Chef Tips

• Beat the egg white until stiff peaks form before the syrup is ready. You need it waiting and ready to go the moment the syrup hits temperature.
• Pour the hot syrup in a thin, steady stream while beating constantly. Dumping it in all at once cooks the egg white into scrambled bits.
• A stand mixer makes this much easier than a hand mixer. You need one hand free to pour the syrup.
• Spread the icing quickly once it’s done. It sets as it cools and becomes difficult to work with if you wait too long.

Variations

• Chocolate marshmallow icing: Fold in melted semisweet chocolate at the end for a rich, glossy chocolate marshmallow finish.
• Toasted marshmallow look: Once iced, use a kitchen torch to lightly brown the peaks for a toasted marshmallow appearance.