jar of jam swiss buttercream

Have I ever told you my love affair with buttercream frosting?

buttermilk brown sugar vanilla cake, strawberry jam swiss buttercream, triple berry marshmallows

Once upon a time, I loved the classic American powdered sugar and butter frosting. It was delicious, buttery and yes, maybe a bit too sweet. But it wasn’t fickle, it always worked. Dependable is the word.

And then the Robicellis came into my life. They make my most favorite cupcakes in New York City. Powdered sugar? They don’t need no stinkin’ powdered sugar. They’re pastry chefs! They use fancy-pants varieties of buttercream and it shows. Because the frosting they create are magical.

Except, strike the fancy-pants. Now that I’ve made swiss buttercream in my home, I realize it’s not so fancy. And it’s not so difficult either. The results are spectacular, truly. As a double whammy of awesome, in the process of making this buttercream I used up an entire jar of strawberry rhubarb jam from last summer. I am smitten with this frosting. Any time I’m searching for a fruity flavor addition to a fancier cake, I have a feeling this recipe will be my answer.

From the smiling face of the birthday girl I made this cake for, it was a success. It makes me grateful for the mistake that led to this frosting. The delectable Apt 2B Baking Co recently posted a brown sugar buttermilk cake with roasted strawberry frosting that I fully intended on making as-is. But readers, here’s some dumb advice: don’t roast while sleepy. My little strawberries turned to blackened pebbles and I felt a fool. Ever grateful for my stocked larder, I decided to give jam a try. Pureed a bit, my barely sweetened strawberry rhubarb jam was a fantastic substitution.

stand mixer whipping up swiss buttercream

Since I made no changes to Yossy’s fantastic cake recipe, today is just about my frosting adaptation. Paired with her cake or any other, this buttercream will knock your socks off. Fruity, silky smooth, buttery but not too sweet. Dream frosting, if I do say so myself.

jar of jam swiss buttercream

Yield: enough frosting for a 2-3 layer cake, plus a little extra


  • 5 egg whites
  • 1 1/4 cups, 250 grams granulated sugar
  • 1/4 teaspoon kosher salt
  • 1 pound unsalted butter, room temperature and cubed
  • 1 cup, 8 oz jam, pureed


  1. In the bowl of your stand mixer [or a large heatproof bowl], combine the egg whites and granulated sugar. Place the bowl over a small pan of simmering water. [Make sure the bottom of the bowl is not making direct contact with the water - you want the steam to warm the mixture not the water.] Whisk the egg mixture continuously until the sugar has dissolved, about 5-7 minutes.
  2. Place the bowl in the stand mixer and using the whisk attachment, whisk until the egg whites have formed stiff peaks, about ten minutes. The mixture should be room temperature.
  3. Switch to the paddle attachment and turn the mixer on low. Add the salt. Now it's time for butter -two tablespoons at a time, add the butter and mix until smooth.
  4. As the butter is added, you may reach a time where the frosting looks curdled - but don't despair! This happened to me. Turn your mixer to high speed for a few minutes and just keep whipping. It will come back together in time.
  5. Once the butter is fully incorporated, slowly drizzle in the pureed jam. Mix until the jam is completely incorporated, no errant streaks of color existing.
  6. Refrigerate for about 15 minutes before frosting the cake, it will be very soft straight from the mixer.

5 Responses

  1. Love it! I do this with straightforward buttercream & it works like a charm–just have to watch the amount of jam you add or it thins out too much.

  2. This sounds amazing!! I will have to give it a try 😀

  3. There’s nothing better than seeing a happy birthday girl with a slice of homemade cake. Nice work, Emily!

  4. That’s the beauty of the swiss buttercream. I started out with 4 ounces of jam but it didn’t seem too runny. So I slowly streamed in more, until I used up the whole jar. Such awesome flavor.

  5. Thanks! Thank you for the awesome inspiration and a great cake. I love buttermilk and vanilla, it was great. And one day, I’m going to make that roasted strawberry frosting. I just won’t burn my berries that time.

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