Marshmallow buttercream frosting is a soft, fluffy buttercream made by beating 1 cup of butter with 2 cups of marshmallow creme (marshmallow fluff), 2½ cups powdered sugar, vanilla, a splash of cream and a pinch of salt. It takes about 10 minutes with a mixer and makes enough to frost 12 cupcakes or fill and frost one 8 inch two layer cake.
It tastes like a marshmallow beaten into buttercream, and it is lighter and less sugary than a plain powdered sugar buttercream. One thing decides how it turns out. Butter temperature.
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One cup (226 g) of unsalted butter carries 2 cups of marshmallow creme. The butter gives the frosting its body. The creme brings air, gloss and that stretchy marshmallow pull you see when you lift the spatula out of the bowl and the frosting follows it up in soft strands. Powdered sugar is there to thicken it, and 2½ cups is less than most American buttercreams use for the same butter, which is why this one tastes gentler.
Marshmallow creme is mostly sugar syrup whipped with egg white. That makes it soft and sticky. It also makes this buttercream more sensitive to heat than a plain one. Use butter at about 65°F: a finger pressed into it leaves a dent but does not slide through. Butter that is shiny or greasy on the outside will give you a soupy frosting that slumps off cupcakes.
Keep the jar of creme at room temperature too. Cold creme seizes. To measure it without a fight, spray the measuring cup and spatula lightly with oil, or skip measuring: a 7 ounce jar is about 2 cups. For UK bakers, that is about 200 g of Marshmallow Fluff, and the powdered sugar is roughly 300 g of icing sugar.
Can You Make Marshmallow Buttercream With Real Marshmallows?
Not well. Bagged marshmallows have to be melted first, and as melted marshmallow cools it firms up and turns stringy, so it never blends smoothly into soft butter. You end up with lumps and a frosting that tightens as it sits. If you want marshmallow flavor from scratch, make a batch of homemade marshmallow cream and use 2 cups of it, cooled to room temperature, in place of the jar.
If what you want is a frosting that tastes like a toasted marshmallow and can be torched, the cooked marshmallow frosting made with egg whites and hot sugar syrup is the better recipe.
Mixing Marshmallow Buttercream, Minute by Minute
Beat the softened butter on medium speed for 2 to 3 minutes, until it turns pale and creamy. Add the marshmallow creme and beat for about 2 minutes more, scraping the bowl so no streaks of creme stay stuck to the sides.
Add the powdered sugar about 1 cup at a time. Start on low. Raise the speed once it disappears. Sift it first if it looks lumpy, because unsifted clumps of powdered sugar are the usual reason a buttercream feels gritty on the tongue even after a long whip.
Mix in 1 teaspoon vanilla and ¼ teaspoon salt for about a minute. Then add 1 tablespoon heavy cream or milk, check the texture, and add the second tablespoon only if it still feels stiff. Finish by whipping on medium high for 2 to 3 minutes. Do not skip it.
It is ready when it looks pale and slightly glossy, holds a soft peak on the spatula, and a spoon dragged through the bowl leaves ridges that slowly relax. Wet looking? It is too warm, not overmixed.
Marshmallow Buttercream vs Marshmallow Frosting vs American Buttercream
- Marshmallow buttercream (this recipe): butter plus marshmallow creme. Soft, fluffy, pipes swirls, moderately sweet. Holds at cool room temperature for a few hours.
- Cooked marshmallow frosting: egg whites and hot syrup, no butter. Very light and glossy, can be torched, best eaten the day it is made.
- American buttercream: butter and a lot of powdered sugar. Sweeter and stiffer, crusts on the outside, the most heat tolerant of the three.
If you want something even less sweet, ermine frosting uses a cooked milk and flour base, and Swiss meringue buttercream is the smoothest choice for sharp cake edges.
When Marshmallow Buttercream Turns Soft, Stringy or Grainy
- Too soft to pipe: warm butter or too much cream. Chill the bowl for 10 to 15 minutes, then re-whip for 30 seconds. If it is still loose, beat in more powdered sugar 2 tablespoons at a time.
- Sticky strings of creme: the creme or butter was cold. Keep beating, and if the strings stay, warm the outside of the bowl for a few seconds with a warm towel.
- Curdled or broken look: the butter was colder than the rest. Warm the bowl slightly the same way and beat until smooth.
- Gritty: lumps of powdered sugar. Sift the sugar next time; a longer final whip helps a little.
- Dense or heavy: it missed the final whip. Whip it now.
- Too sweet: do not skip the ¼ teaspoon salt. A few drops of lemon juice also cut the sweetness without tasting lemony.
Cupcakes, Layer Cakes and Cookies to Frost
One batch pipes tall swirls on 12 cupcakes. For neater swirls, chill the frosting for 10 to 15 minutes before it goes in the piping bag. Chocolate cupcakes and vanilla cupcakes both suit it, and the marshmallow flavor is strong next to chocolate, a bit like a s’more.
For an 8 inch two layer cake, use about a third of the batch between the layers and the rest on the top and sides. It also sandwiches sugar cookies and makes a soft filling for whoopie pies. For another marshmallow cupcake, the popcorn cupcakes with toasted marshmallow are a fun next bake.
Chocolate, Strawberry and Other Flavors
Beat in 2 tablespoons cocoa powder for a light chocolate marshmallow buttercream. For strawberry, add a few tablespoons of finely ground freeze dried strawberries. A little almond extract next to the vanilla tastes like bakery cake, and lemon zest makes it fresher. For a different base flavor altogether, coconut buttercream frosting pairs well with the same cakes.
How Long Marshmallow Buttercream Keeps
A frosted cake holds its shape at cool room temperature for a few hours. That covers a party. In a warm room it softens faster than American buttercream, so keep the cake in the fridge until an hour before serving.
Leftover frosting keeps in an airtight container in the fridge for up to 3 days. Let it come back to room temperature, then re-whip it for a minute so it is fluffy again. You can freeze it too; thaw it overnight in the fridge and re-whip before using.
Marshmallow Buttercream Quick Questions
Is marshmallow creme the same as marshmallow fluff?
Yes. Fluff is a brand name.
Will marshmallow buttercream crust?
Barely. It has much less powdered sugar than American buttercream, so the surface stays soft and a little tacky even after a few hours on the counter.
Can I color it?
Yes. Use gel coloring. Liquid thins it.
Marshmallow Buttercream Frosting Recipe
This marshmallow buttercream frosting is a fluffy buttercream made with softened butter, marshmallow creme (marshmallow fluff), powdered sugar, vanilla, a splash of cream and a pinch of salt. It takes about 10 minutes with a mixer and makes enough for 12 cupcakes or one 8 inch two layer cake, with a soft, glossy texture that spreads easily and pipes neat swirls. The butter is beaten pale first, then the creme and sugar go in, and a final 2 to 3 minute whip makes it light. Use this marshmallow fluff buttercream on chocolate or vanilla cupcakes, between cake layers, on sugar cookies, or as a filling for whoopie pies. Add 2 tablespoons cocoa for a chocolate version, and keep leftovers in the fridge for up to 3 days.
Ingredients
- 1 cup (226 g) unsalted butter, softened
- 2 cups marshmallow creme (marshmallow fluff)
- 2½ cups powdered sugar
- 1 teaspoon vanilla extract
- 1–2 tablespoons heavy cream or milk
- ¼ teaspoon salt
Instructions
STEP 1: BEAT THE BUTTER: Place softened butter into a large mixing bowl. Use a hand mixer or stand mixer on medium speed for 2 to 3 minutes until the butter becomes pale and creamy. Proper creaming builds the base structure that supports the final fluffy texture.
STEP 2: ADD THE MARSHMALLOW CREME: Add marshmallow creme to the whipped butter. Mix on medium speed for about 2 minutes until the mixture becomes smooth and airy. Scrape the sides of the bowl to ensure even blending.
STEP 3: ADD THE POWDERED SUGAR: Add powdered sugar gradually, about one cup at a time. Start mixing on low speed to prevent the sugar from scattering, then increase to medium speed after the sugar begins to incorporate. Continue mixing until the frosting thickens and smooths.
STEP 4: ADD VANILLA AND SALT: Pour in vanilla extract and add salt. Mix for about 1 minute until the flavorings distribute evenly through the frosting.
STEP 5: ADJUST THE TEXTURE: Add 1 tablespoon heavy cream or milk and mix until incorporated. Check the consistency. Add an additional tablespoon if needed until the frosting becomes smooth and spreadable.
STEP 6: WHIP FOR EXTRA FLUFFINESS: Increase mixer speed to medium-high and whip the frosting for 2 to 3 minutes. This step adds air and creates the light, cloud-like texture that spreads easily and pipes neatly.
Notes
Use butter at about 65°F, soft enough to dent but not greasy; warm butter makes the frosting too soft to pipe. Keep the marshmallow creme at room temperature so it blends without stringy clumps; a 7 ounce jar is about 2 cups. Lightly oil the measuring cup and spatula so the creme slides off. Add the cream 1 tablespoon at a time; for a thicker frosting, use less. For piping decorations, chill the frosting for 10 to 15 minutes to help it hold sharper shapes. Store leftover frosting in an airtight container in the refrigerator for up to 3 days. Bring to room temperature and re-whip before using.
