Marshmallow Buttercream Frosting
Creamy, fluffy, marshmallow-y frosting. Delicate yet sturdy enough to frost and fill a cake, this recipe comes together in ten minutes and adds a great twist to any cake.
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The story
I love marshmallow. Like, a lot. On my first date with my husband, we got ice cream after dinner and it came out that we both loved marshmallow. In fact he introduced me to one of the only local places with marshmallow sauce.
I’m pretty sure that’s the moment I fell in love with him.
That might be a slight exaggeration, but it just shows you how much I love marshmallow. And you can do so much with it. S’mores and anything s’mores flavored top the list for me. In fact, I just found out Tillamook discontinued their Fireside S’mores ice cream and I compared it to the day Alan Rickman died.
Is that overly dramatic? I don’t think so.
Weirdly, I have a traumatic history with marshmallow frosting. My first try was gummy and hard. I have a great marshmallow meringue recipe (basically homemade marshmallow fluff), but it doesn’t work well as a legit frosting. You can use it whimsically as a decorative outer frosting or on cupcakes. But it’s finicky and very well may cause your cake to slide around.
That’s what it did when I tried to use it as the filling for my husband’s 30th birthday cake at his surprise party. Basically, it tried to fall apart even in the fridge and was a leaning tower of cake by the time we sang to him and I nearly cried.
After a lot of research and experimenting, I’ve found a perfect marshmallow balance. Even though it uses jarred fluff (contrary to my made-from-scratch goals), I love it enough to make this exception.
Update: I now have a homemade marshmallow fluff that works beautifully in this frosting! It has just the right consistency to make this frosting marshmallowy yet sturdy. However, neither version does well if you’re stacking a super tall or heavy cake—those tend to require extra sturdy fillings and outer frostings to hold it all together.
Tips for this recipe
Adjust the ratio to your liking
You can increase or decrease the amount of butter to either dilute or amplify the taste of marshmallow. Beware using less than 4 ounces of butter, as you’ll get a pretty loose frosting that may not want to stay on your cake.
Add the marshmallow after the powdered sugar
I’ve made this several ways, and I discovered that the marshmallow doesn’t blend well if you add it directly to the butter. Most buttercream based frostings do best with this method, for science-y reasons I don’t know offhand but which I know have to do with the fat content and emulsion of fats. Just trust me—it’s a simple recipe but you want to follow the very few directions it has.
Taste as you go
Marshmallow fluff is naturally very sweet. You can use homemade, which is less sweet, but it also is less sturdy. Thus, check for sweetness as you add powdered sugar. If needed, put the whole bowl in the fridge for 5 minutes then keep mixing. Or, refrigerate it after the final whip/before you frosting your cake. You can refrigerate or even freeze your frosted cake to set the frosting. You can refrigerate frosted cupcakes for up to 30 minutes, but don’t go longer and don’t freeze them, as it dries them out. The cupcakes here were not refrigerated, but I did refrigerate the frosting before and after putting it in the piping bag.
Don’t over-soften your butter
Trust me, you want your butter to be just barely softened. It shouldn’t be shiny and should definitely give some resistance when you press into it. Otherwise, you’ll struggle to get a good consistency.
Use with any cake (or brownie or cookie…)
The cupcakes you see here are a small-batch version of my blackout cake, to create a cookies and cream cupcake for a dear friend. But I’ve used this with my regular chocolate cake as a hot chocolate style cake (or with caramel drizzle for a scotchmallow cake or with peppermint extract for a peppermint hot chocolate cake). Pairing it with vanilla cake or cupcakes may seem like a stretch, but throw in some coconut (plain or toasted) and you’ve got a yummy coconut cake! I don’t do red velvet too often, but this is a great, non-refrigerated alternative to classic cream cheese frosting. Or, pair with brownies or as a cookie sandwich filling, because who doesn’t want more marshmallow in their life?
My buttercream tools
Here are my must-have tools I use for making this buttercream. Affiliate links provided.
Marshmallow Buttercream Frosting
- total time: 10-15 minutes
Servings: about 2 cups, enough to fill and frost an 8” or 9” cake, or 24 cupcakes (use a 1.5 batch if you want thicker frosting)
Ingredients:
- 1 cup (2 sticks) unsalted, European style butter, room temperature
- 2-4 cups powdered sugar
- ½ batch marshmallow fluff (or one 7oz jar store bought marshmallow cream)
- ¼ teaspoon sea salt
- ½ tablespoon vanilla extract (optional, enhances the marshmallow flavor)
- 1-2 tablespoons heavy whipping cream, or as needed (I omitted for this recipe due to the heat)
Instructions:
- If using homemade marshmallow fluff, make that first. You can immediately start on the buttercream once the fluff is done.
- In the bowl of your stand mixer fitted with the paddle attachment or in a large mixing bowl using your hand mixer, cream butter on high until smooth, about 1 minute.
- Scrape bowl with a rubber spatula then add in powdered sugar, 1 cup at a time. Blend on low then slowly increase speed to high and mix until smooth before adding more. After 2 cups, scrape the bowl then add in the marshmallow fluff. Mix on high until well-blended, about 30-60 seconds. Add salt and vanilla, if using, and blend until fully incorporated.
- At this point, taste to see if it needs more sugar. If it’s sweet enough but not holding its shape like in the photos, you can fix this with some refrigeration. If it’s too stiff or grainy, mix in heavy cream one splash at a time until smooth.
- Once taste and texture are to your liking, scrape the bowl then mix on high for 1 minute, until light and fluffy. Avoid mixing longer, as it can eventually turn gummy. If you need a truly white frosting, you can also add a teeny tiny quinoa-grain-sized drop of violet gel food coloring before whipping. After it’s fluffy and creamy, stir by hand with a wooden spoon or rubber spatula for 1 minute to release any large air bubbles that formed.
Frost cake or cupcakes and enjoy! Frosting can be stored in the fridge in an airtight container for 1-2 weeks or in the freezer for 1-2 months. To use chilled frosting, let come to room temperature then whip for about a minute to fluff back up.
