Coffee Swiss Meringue Buttercream
This coffee Swiss meringue buttercream is delicious and light, with a sophisticated coffee flavor that beautifully enhances cakes and cupcakes. As a Swiss meringue-based frosting, it’s less sweet than traditional American buttercream recipes, so you can use it generously without it being overwhelmingly sweet.
Swiss buttercream
Swiss meringue buttercream (SMBC) is created by gently heating egg whites and sugar in a double boiler until the sugar dissolves. This mixture is then whipped into a stiff meringue.
After that, plenty of room-temperature butter is gradually whisked into the meringue until the mixture transforms into a perfect, fluffy buttercream.
Ingredients
This buttercream is made with simple ingredients. The actual measurements for this coffee Swiss meringue buttercream are in the printable recipe card at the end of this post. Here’s a quick rundown of what you’ll need:
- Large egg whites. You can use fresh large eggs or liquid egg whites.
- Granulated sugar (you can also use soft brown sugar for a deeper flavor)
- Room temperature butter. This can be salted or unsalted butter.
- Instant coffee granules / instant espresso powder
- Warm milk to dissolve the coffee in
- Vanilla extract
- Salt. Decrease this if using salted butter.
Equipment
To make the coffee meringue buttercream, you’ll need a stand mixer with whisk and paddle attachments. Alternatively, you could use a large bowl and a hand mixer, but this method is much harder as the frosting requires a lot of mixing. This frosting is not suitable for a hand whisk.
Method
Egg Whites
Bring a medium saucepan with 1-2 inches of water to a simmer. Dissolve the instant coffee in warm milk and set aside.
Combine egg whites and granulated sugar in the metal bowl of a stand mixer or other heatproof bowl. Balance the bottom of the bowl over the simmering water bath.
Whisk continuously as the egg whites warm up, ensuring all the sugar has dissolved or the temperature reaches 160°F (71°C) on an instant-read thermometer.
Be sure to keep stirring to prevent any egg whites from overcooking on the edges of the bowl.
Once the sugar has dissolved, place the bowl in your stand mixer fitted with the whisk attachment.
Beat on medium-high speed until the stiff peak stage and the meringue cools to room temperature.
Next, gradually add a few pieces of softened butter to the meringue base with the mixer still on medium-high speed.
At this stage, the frosting may appear to separate or curdle – don’t panic!
Just continue beating the mixture until it becomes a thick and cohesive buttercream.
This process can take time, so don’t give up if it seems slow – it will come together.
Once the mixture is thick and cohesive, beat in the coffee, vanilla, and salt until the frosting is thick and fluffy.
At first, the coffee will look like it doesn’t want to mix into the frosting, but it will.
Finally, switch to the paddle attachment and beat on low for 10 minutes to knock out the larger air bubbles in the buttercream.
Frosting Tips
- Ensure your bowl is clean when adding the egg whites and that no yolk gets into the mixture, as this can stop you from achieving stiff peaks.
- Avoid making this buttercream on hot days. If you need to, make it in the morning when temperatures aren’t too warm yet.
- Keep whisking the egg whites as they cook over the hot water so you don’t scramble them.
- Make sure both your butter and meringue are at room temperature before beating in the butter.
Serving
This recipe makes around 4 ½ cups of frosting, enough to frost a double-layer 9-inch cake or a three 8-inch layer cakes. It can also frost 24 cupcakes.
Storing
Store the coffee buttercream in a covered bowl or airtight container at room temperature for 1-2 days, provided the room isn’t too warm. If your kitchen is hot, store it in the fridge or freezer until needed.
It will need to be whipped again before piping. The frosting can be frozen and wrapped tightly with plastic wrap for up to 3 months.
Rewhipping the Buttercream
As the buttercream cools in the refrigerator, it will harden due to the solidifying butter. To make it creamy again, bring it back to room temperature and whip it. You can either leave it to warm up for a few hours or gently warm the bowl of buttercream over a hot water bath until the edges in the bowl start to melt. Once the edges have melted, place the bowl back in the stand mixer and whip it for 3-5 minutes until creamy again.
You can leave it to sit out and warm up for a few hours, or gently warm the buttercream bowl over a hot water bath until the buttercream edges in the bowl begin to melt. Once the edges have melted, place the bowl back in the stand mixer and whip it for 3-5 minutes until creamy again. If the mixture appears to split and become curdled, the butter is still too cold and will need a little more warming.
If it becomes soupy and liquid, it has warmed too much, so place it back in the fridge to cool it down. Whichever way it swings, there’s a fix for it, you need to get it at the right temperature.
Variations
- Chocolate Swiss Meringue Buttercream. This version mixes dark chocolate, milk, or white chocolate into the frosting recipe. The melted chocolate makes it taste like airy chocolate mousse.
- Brown Butter Swiss Meringue buttercream. Toast some of the butter to caramelize the milk solids. This adds a delicious nutty, caramel-like flavor to the frosting.
For another not-too-sweet frosting recipe, try this Ermine frosting, or try this Brown Butter Cream Cheese Frosting
Coffee Recipes
More coffee treats!
Coffee Swiss Meringue Buttercream
This coffee Swiss meringue buttercream is delicious and light, with a sophisticated coffee flavor that beautifully enhances cakes and cupcakes. This enough to frost a 2 layer 9-inch cake or 3 layer 8-inch cake, or 24 cupcakes.
Ingredients
- 10g (1 1/2 Tablespoon) instant coffee granules
- 30g (2 Tablespoons) warm milk
- 5 large egg whites
- 250g (1 ¼ cup) granulated sugar or soft brown sugar
- 340g (1 ½ cups) unsalted butter, room temperature, cut into cubes
- 1 teaspoon vanilla paste or extract
- 1/4 teaspoon of salt
Instructions
- Dissolve the instant coffee in warm milk in a small bowl and set aside.
- Bring a medium saucepan with 1-2 inches of water to a simmer.
- Combine egg whites and granulated sugar in the metal bowl of a stand mixer or other metal bowl. Balance the bottom of the bowl over the simmering water. Whisk continuously as the egg whites warm up, ensuring all the sugar has dissolved or the temperature reaches 160°F (71°C) on an instant-read thermometer. Be sure to keep stirring to prevent any egg whites from overcooking on the edges of the bowl.
- Once the sugar has dissolved, place the bowl in your stand mixer fitted with the whisk attachment. Beat on medium-high speed until the stiff peaks form and the meringue cools to room temperature.
- Next, gradually add the softened butter to the meringue, a few pieces at a time, with the mixer still on medium-high speed.
- At this stage, the frosting may appear to separate or curdle – don't panic! Just continue beating the mixture until it becomes a thick and cohesive buttercream. This process can take time, so don't give up if it seems slow - it will come together.
- Once the mixture is thick and cohesive, beat in the coffee mixture, vanilla, and salt until the frosting is thick and fluffy. At first, the coffee will look like it doesn't want to mix into the frosting, but it will.
- Switch to the paddle attachment and beat on low for 10 minutes to knock out the larger air bubbles in the buttercream.
- The frosting can be made in advance and stored in the refrigerator or freezer. It will need to be re-whipped before using. See the notes below.
Notes
Rewhipping cold SMBC
As the buttercream cools, it will become hard as all the butter there has solidified. Bring it back to room temperature and whip it to make it creamy.
You can leave it to sit out and warm up for a few hours, or gently warm the buttercream bowl over a hot water bath until the buttercream edges begin to melt.
Once the edges have melted, place the bowl back in the stand mixer and whip it for 3-5 minutes until creamy again. If the mixture appears to split and become curdled, the butter is still too cold and will need more warming. You can warm the edges over a hot water bath again, or remove 1/4 cup of the frosting and warm it until liquid in the microwave. Add the warmed frosting back to the bowl and whip.
If the buttercream becomes soupy, it has warmed too much, so place it back in the fridge to cool it down. Whichever way it swings, there's a fix for it, you need to get it at the right temperature.
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