Your step-by-step guide to the latest baking trend.

By Ana Calderone
November 27, 2019 02:40 PM
Credit: Ana Calderone

You’ve probably heard that baking is a science, but sometimes, it can also seem like magic.

I’m not talking about the flashy, pull a rabbit out of a hat kind of magic, but more like the DIY card trick with intricately-planned secrets only the dealer is privy to. In this case though, the dealer is a baker, and the trick is marble buttercream.

I came across this mesmerizing frosting technique from Mijji Song of Mijji Cakes (@mijjicakes) during one of my frequent bouts of Instagram scrolling.

I’d seen marble cakes before as the trend has picked up steam over the past few years, but a quick Google search never lead me to an easy tutorial that seemed like a good use of time. Some bakers suggest marbling your buttercream on a sheet of parchment paper and then transferring it to your cake in one fell swoop. That struck me as messy, with way too much room for error. Others called for mixing different colored fondant together, but I maintain that despite how pretty it looks, no one likes the taste of fondant.

Song’s method involves gently mixing three or four shades of buttercream together without fully blending them, applying them to a cake like you normally would, and then freezing the cake for twenty minutes. Once you say abracadabra three times and take it out of the freezer, you have a marble buttercream cake. I’m kidding. There isn’t actually any sorcery involved (that I know of).

At this point your cake will look like a jumbled mess. It’s when you scrape the outer layer of frosting off that you reveal the marbling effect underneath. It’s enchanting to watch even if you’ve never picked up a spatula and simply enjoy cake videos for the 30 seconds of mindless entertainment — and even more satisfying if you’re a baker watching your hard work come to fruition in real life.

If you’re the latter, I collected some tips from Song and from my own attempts — both successful and unsuccessful — to help you master it.

Make sure your buttercream is smooth, but not thin.

Song recommends using Swiss or Italian meringue buttercream — American buttercream’s less sweet but more advanced counterparts — because they have a silkier texture. Keeping that in mind, I opted for a cream cheese frosting on my first attempt thinking it’d be smooth enough. It could just be my go-to recipe, but the consistency was actually too creamy that my colors mixed together before I could even apply them to the cake and ruined all chances of really defined swirls.

I’m happy to report that American buttercream worked just fine though, as that’s my preferred frosting (and same for those who eat my desserts on the regular). You’re looking for a slightly stiffer buttercream, so add your milk in sparingly and don’t be afraid to add an extra tablespoon or two of powdered sugar to get the right consistency.

No matter what buttercream recipe you use, keep in mind that you want as few air bubbles as possible. “To achieve this, I put the buttercream in an electric mixer on the lowest setting and let it run for about 10 minutes,” suggests Song. You can also beat the buttercream up the sides of your bowl by hand with a rubber spatula to get rid of any bubbles.

Dye at least two different shades of buttercream and leave the rest white.

For her cakes served in the San Francisco Bay area, Song generally divides her frosting into white, a light shade, medium shade, and a dark shade. I only had the patience to dye two shades of pink for my cake and I was happy with the result, so I say save yourself from dirtying the extra bowl and do that.

Use a thicker crumb coat than usual.

In the final step, you’ll scrape a decent amount of frosting off to expose the marbling, so be generous in the beginning. I opted for a thicker crumb coat so no matter how much I shaved off, you likely wouldn’t see my cake layers underneath. Song stresses that the colored layer of frosting should be thicker than usual too. The more frosting you add, the more chances of that beautiful effect coming through.

Don’t be afraid to use some elbow grease.

When my cake came out of the freezer and I started scraping the outer layer off, I was convinced I messed something up again. I actually said out loud (to no one in particular), “What a waste of butter.” The frosting looked more like a watercolor painting rather than a slab of marble. It wasn’t until I applied a decent amount of pressure that I started seeing it.

It took me about 20 minute of continuous scraping, but this part is all about personal preference. Stop when you’re happy with the way it looks.

Get the full recipe below, and watch the videos above to see how it’s done.

Marble Buttercream Cake

4 sticks unsalted butter, at room temperature
2 lbs. confectioners’ sugar
2-3 Tbsp. whole milk
4 tsp. pure vanilla extract
1 tsp. salt
3 (6-inch) layers of your favorite cake, baked and cooled
Gel food coloring

1. Beat the butter in the bowl of a stand mixer fitted with a paddle attachment on high speed until smooth, about 1 minute. With the mixer on low, gradually add the sugar, alternating with the milk, 1 tablespoon at a time. Add the vanilla and salt and mix on high speed until no lumps remain, about 3 minutes. Turn the mixer to low and beat for 10 minutes.

2. Place one cake layer on a rotating cake stand. Spread ½ cup buttercream on top in an even layer. Repeat with remaining layers. To apply a crumb coat, apply about 2 cups buttercream on top and sides of cake. Remove excess frosting with a metal bench scraper. Transfer the cake to the refrigerator and chill for 30 minutes.

3. Divide remaining buttercream equally into 3 medium bowls. Add 2-3 drops of food coloring to one bowl, 5-6 drops to another bowl, and leave the remaining bowl white. In a large bowl, gently fold half of each color together with a small offset spatula. Remove the cake from the refrigerator. Apply mixed buttercream to the top and sides of cake with the spatula. Repeat folding the remaining buttercream together and applying to your cake. Smooth sides with a metal bench scraper. (It will look like your colors have blended together, but that’s okay.) Transfer the cake to the freezer for 20 minutes.

4. Remove cake from the freezer. Scrape the outer layer of the frozen buttercream off with a metal bench scraper. Repeat until marble swirls appear.

Active time: 1 hour
Total time: 2 hours (includes freezing time)