Recipe For Seafoam Icing: Light and Fluffy Marshmallow Topping

This marshmallow-based topping delivers a cloud-like texture that’s perfect for cakes and cupcakes.

With just a few simple ingredients and 10 minutes of prep, you’ll have a light, airy icing that holds its shape beautifully.

Ingredients for Recipe for Seafoam Icing

These few simple ingredients transform into a light, cloud-like topping for desserts.

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The marshmallows are critical here. Jet-Puffed mini marshmallows dissolve most smoothly, but any mini variety works if fresh. Avoid large marshmallows—they take longer to melt and can leave lumps. For the sugar, Domino or C&H fine granulated ensures a silky texture. Heavy cream should be at least 36% fat for proper whipping; Organic Valley is a reliable brand.

No corn syrup? Honey or agave at the same amount works, though the texture may be slightly less stable. Out of mini marshmallows? Chop regular ones finely—just know they won’t melt as uniformly. For a dairy-free version, coconut cream and vegan butter can substitute, but the flavor profile shifts. Vanilla can be swapped for almond extract for a different twist.

This icing holds at room temperature for 2 hours but should be refrigerated otherwise. Store in an airtight container for up to 3 days. Rewhip briefly before using if it separates. Freezing isn’t recommended—it alters the airy texture.

Step-by-Step Instructions for Seafoam Icing

Master this technique for a light, airy topping that holds its shape beautifully.

Step 1: Prepare the Sugar Syrup

In a medium saucepan, combine the 1.5 cups Granulated Sugar, 2 tbsp Corn Syrup, and 2 tbsp Water. Stir just enough to moisten the sugar—avoid stirring once heating begins, as this can cause crystallization.

Cook over medium heat until the mixture reaches 240°F on a candy thermometer. Watch for the syrup to turn clear and develop small bubbles around the edges. This stage ensures the sugar dissolves completely before boiling.

Step 2: Melt the Marshmallow Base

While the syrup cooks, prepare the marshmallow mixture. In a heatproof bowl, combine the 2 cups Mini Marshmallows, 0.5 cup Heavy Cream, 0.5 cup Unsalted Butter, and 0.25 tsp Salt.

Place the bowl over a pot of simmering water (double boiler method) and stir until the marshmallows melt completely and the mixture becomes smooth. Remove from heat and stir in the 1 tsp Vanilla Extract. The mixture should be glossy and free of lumps.

Step 3: Combine Syrup and Marshmallow Mixture

With a hand mixer or stand mixer fitted with the whisk attachment, beat the melted marshmallow mixture on medium speed for 30 seconds to cool it slightly. This prevents the hot syrup from shocking the mixture.

Slowly pour the hot sugar syrup down the side of the bowl in a thin, steady stream while continuing to beat on medium-high speed. The mixture will become glossy and begin to thicken. Beat for an additional 5-7 minutes until the icing holds soft peaks when the whisk is lifted.

Step 4: Whip to Stiff Peaks

Increase the speed to high and continue beating for another 3-5 minutes. The icing should turn white and fluffy, holding stiff peaks that maintain their shape. Watch for the texture to change from sticky to light and airy.

Stop mixing once the desired consistency is reached. Over-whipping can cause the icing to become grainy or separate. The finished product should be glossy, smooth, and spreadable, with a marshmallow-like texture.

Step 5: Use Immediately for Best Results

Use the seafoam icing right away to frost cakes, cupcakes, or desserts. It sets quickly at room temperature, so work efficiently. For piping, transfer the icing to a pastry bag fitted with your desired tip.

If the icing begins to stiffen before use, gently rewhip it for 10-15 seconds to restore its spreadability. Store any unused icing in an airtight container at room temperature for up to 2 days, though it’s best used fresh for optimal texture.

Make-Ahead Tips for This Recipe

🔪 Week Before

For the smoothest prep, start by gathering all non-perishable ingredients like sugar, corn syrup, and cream of tartar. Check your pantry for these staples and make a shopping list for anything missing. If you’re using a stand mixer, ensure the whisk attachment is clean and ready to go.

⏰ Day Before

Measure out all dry ingredients and set them aside in airtight containers. This includes the granulated sugar and corn syrup. If your recipe calls for vanilla extract or other flavorings, have those prepped and within reach. Pro tip: 💡 Lightly grease your mixing bowl and whisk with cooking spray to prevent sticking later.

👨‍🍳 Day Of

Begin by cooking the sugar syrup mixture to the correct temperature (240°F or soft-ball stage). While it heats, beat your egg whites and cream of tartar to stiff peaks. Once the syrup is ready, slowly pour it into the egg whites while mixing continuously. This step requires focus, so clear your workspace beforehand.

✨ Last-Minute Tasks

After the icing comes together, use it immediately for best results, as seafoam icing sets quickly. If needed, store it in an airtight container at room temperature for up to 2 hours before using. Avoid refrigeration, as it can cause the icing to harden prematurely.