Fluffy Strawberry Marshmallow Frosting: A Cloud-Like Topping for Cakes and Cupcakes.

When it comes to frosting, most people fall into two camps: the devotees of rich, dense buttercream and those who prefer something lighter and more airy. This strawberry marshmallow frosting is the perfect middle ground. It carries the structural integrity needed to pipe beautiful swirls on a cupcake, but it has the ethereal, melt-in-your-mouth quality of a homemade marshmallow.

By using a base of marshmallow crème (often called fluff) and a concentrated strawberry reduction, we avoid the artificial, neon-pink flavors found in store-bought tubs. Instead, you get a frosting that tastes like fresh summer berries and toasted vanilla. It is exceptionally smooth, glossy, and—most importantly—it isn’t overbearingly sweet, thanks to the slight tartness of the fruit.

Ingredients for Strawberry Marshmallow Frosting

The key to this frosting is ensuring your ingredients are at the correct temperature. If the butter is too cold, the frosting will be lumpy; if it’s too warm, it will lose its structural “puff.”

Unsalted Butter: 1 cup (225g), softened to room temperature.
Marshmallow Crème: 1 jar (7 ounces). This provides the unique “stretchy” and airy texture.
Powdered Sugar: 2 to 2 1/2 cups (240g–300g), sifted.
Fresh or Frozen Strawberries: 1 cup, finely chopped or puréed.
Vanilla Extract: 1 teaspoon.
Salt: A tiny pinch to balance the sugar.
Lemon Juice: 1/2 teaspoon, to brighten the strawberry flavor.

Step-by-Step Instructions

Creating the Strawberry Concentration

To prevent the frosting from becoming runny, you cannot simply add fresh strawberry juice. You must create a reduction. Place your chopped strawberries in a small saucepan over medium-low heat. Simmer them for about 10 to 15 minutes, stirring frequently, until the liquid has evaporated and you are left with about 3 tablespoons of thick, jam-like concentrate.

Press this mixture through a fine-mesh sieve to remove the seeds. Let this strawberry “gel” cool completely. Adding it while warm will melt the butter and ruin the frosting.

Creaming the Base

In a large bowl, or the bowl of a stand mixer fitted with the paddle attachment, beat the softened butter on medium-high speed for about 3 minutes until it is very pale and creamy. Scrape down the sides of the bowl to ensure every bit is aerated.

Add the marshmallow crème to the butter and beat for another 2 minutes. The mixture should look very glossy and voluminous at this stage.

Adding the Flavor and Structure

Turn the mixer to low and gradually add 2 cups of the sifted powdered sugar. Once incorporated, add the cooled strawberry reduction, vanilla extract, lemon juice, and salt.

Increase the speed to medium-high and whip the frosting for another 2 to 3 minutes. If the frosting feels too soft to hold its shape, add the remaining 1/2 cup of powdered sugar. You are looking for a consistency that is light enough to spread but stiff enough to hold a peak.

Flavor and Texture Notes

The first thing you notice about this frosting is the sheen. Unlike standard American buttercream, which can look matte, the marshmallow crème gives this a beautiful luster. The texture is famously “marshmallowy”—it has a slight pull to it but remains incredibly soft on the palate.

The flavor is a sophisticated version of a strawberry milkshake. The reduction provides an authentic berry taste that weaves through the vanilla notes of the marshmallow. Because of the salt and lemon juice, the finish is clean rather than cloying, making it easy to enjoy a second slice of cake.

Tips and Variations

The Freeze-Dried Hack: If you don’t want to bother with a reduction, you can pulse 1 cup of freeze-dried strawberries in a blender until they become a fine powder. Whisk this powder directly into the frosting. It provides an intense flavor and a deep pink color without adding any moisture.
Toasted Marshmallow Version: If you have a kitchen torch, you can lightly toast the outside of the frosting once it’s piped onto your cake for a “campy” bonfire flavor.
Chocolate Strawberry: Use this frosting to fill a dark chocolate layer cake. The bitterness of the cocoa is the perfect partner for the sweet strawberry fluff.
A Bit of Texture: For a more rustic look, don’t strain the strawberry seeds out of your reduction. The small flecks of fruit look beautiful against the pink frosting.

Storage and Make-Ahead Advice

Refrigeration: Because this frosting contains butter and fruit, it should be stored in the refrigerator if you aren’t serving it within a few hours. It will firm up significantly when cold.
Bringing to Temperature: If you’ve made the frosting in advance, let it sit at room temperature for about 30 to 45 minutes before using. Give it a quick whip with a spatula to restore its fluffiness.
Freezing: This frosting freezes surprisingly well. Place it in a freezer-safe bag for up to 2 months. Thaw in the fridge overnight and re-whip before using.

Serving Suggestions

This frosting is versatile enough for almost any baked good, but it truly shines in these combinations:

Lemon Poppy Seed Cupcakes: The tart lemon in the cake and the sweet strawberry frosting create a classic “strawberry lemonade” flavor profile.
Graham Cracker Sandwich Cookies: Pipe a dollop between two graham crackers for an easy, elevated take on a s’more.
Vanilla Bean Sheet Cake: A thick, swooshy layer of this frosting over a simple vanilla cake is an effortless way to make a basic dessert feel like a celebration.

FAQ

Why is my frosting grainy?

This usually happens if the powdered sugar wasn’t sifted. Marshmallow frosting is very smooth, so any lumps in the sugar will be noticeable. If it’s already mixed, you can try beating it for an extra 2 minutes on high speed to help dissolve the crystals.

Can I use regular marshmallows instead of crème?

It is difficult to substitute melted marshmallows because they contain gelatin, which will cause the frosting to set into a rubbery texture as it cools. For this specific “fluff” texture, the jarred crème is the best tool for the job.

Is this frosting stable enough for a tiered cake?

It is stable enough for a standard two-layer cake or cupcakes. However, for a heavy multi-tiered wedding cake, I would recommend using this as a filling and using a sturdier Swiss Meringue buttercream for the exterior “walls” of the cake.

Conclusion

This strawberry marshmallow frosting is a recipe that brings a sense of whimsy to the kitchen. It feels a bit more special than a standard buttercream, and the authentic fruit flavor sets it apart from more industrial-tasting toppings. Whether you are frosting a birthday cake or just looking for a way to use up summer berries, this fluffy, pink cloud of a frosting is a reliable favorite.