This tart and creamy Lemon Buttercream frosting is an intensely fruity and flavorful version of my Swiss meringue buttercream recipe. It's ultra-creamy, stable (meaning it will hold its shape), light, and fluffy. It's made by combining Swiss meringue, unsalted butter, and homemade lemon curd. If you've never tried this type of buttercream before then you should give this a try. Below, I share my foolproof recipe and tips and tricks for making this delicious buttercream.
Why I Love Swiss Meringue Buttercream
- Requires only 6 ingredients. The base recipe requires only 5 basic ingredients for an incredibly creamy buttercream and the lemon curd is the 6th ingredient
- Stable and Pipeable: Holds its shape beautifully for decorating cakes and cupcakes. The stability makes it perfect for making cakes on a warm day. It's less likely to become too soft like American Buttercream.
- Balanced sweetness: The sugar content is less intense than American buttercream, allowing other flavors to shine.
I recommend this buttercream for vanilla, chocolate, and lemon cake. So if you already have a favorite cake recipe, try this buttercream, or try it with these delicious and moist lemon cupcakes. And if you like the combination of raspberry lemon pair it with these incredible and fluffy raspberry cupcakes.
What is Swiss Meringue Buttercream (SMBC)
Swiss meringue buttercream combines Swiss meringue (egg whites and sugar) and butter and it's my favorite buttercream. It's silky smooth, tastes delicious, and it's not too sweet.
Swiss meringue starts with whisking egg whites and sugar in a double boiler over simmering water until it reaches a temperature of 170-175F. This gentle heat cooks the egg whites and sugar, creating a stable and safe-to-eat base.
Unlike French meringue, which relies on whipping the egg whites, the process of cooking the eggs and sugar together for Swiss meringue ensures a more stable meringue. And it doesn't require the hot sugar syrup of Italian meringue, making it a bit easier to prepare.
Once the cooked sugar and egg white base is cooked it's whipped to stiff peaks which can be used as a meringue topping for pies, tarts, and cakes at this point. To make the buttercream, butter is whipped into the meringue until silky smooth with a cloud-like quality, transforming into a delightful frosting perfect for cakes and cupcakes.
My other variations of Swiss meringue buttercream are Raspberry Buttercream and Blackberry Buttercream.
Lemon Swiss Meringue Buttercream Ingredients
Here are the ingredients you'll need for this delicious lemony buttercream frosting:
- Homemade Lemon Curd: Use my recipe for homemade lemon curd. It has an intense lemon flavor from the fresh lemon zest and lemon juice. The recipe makes 2 cups. You won't use it all for this buttercream, but it can be refrigerated for to 2 weeks and frozen for up to a year.
- Egg Whites. The egg whites create the meringue which is the base of the buttercream. Use large egg whites which weigh 30 grams each.
- Unsalted Butter. Butter turns meringue into meringue buttercream. Don’t use salted butter because the salt in the butter will produce an off taste. The butter should be at room temperature (65-68F) when it's added to the meringue. Butter that is too warm (above 72F) will produce a soupy buttercream. For accuracy, you can use an instant-read thermometer to check the temperature. Cut the butter into tablespoon-size pieces before using.
- Pure Vanilla Extract: Vanilla extract makes the lemon flavor in the buttercream more pronounced.
Full ingredients, measurements, and instructions are in the recipe card at the bottom of this post.
How to Make Lemon Swiss Meringue Buttercream
One of the lovely things about Swiss Meringue Buttercream is that is a recipe of perfect proportions. For every large egg white (30 grams), use 1/4 cup of granulated sugar and about 8 tablespoons of unsalted butter.
The lemon curd can be made up to 1 week in advance. You can also use store-bought lemon curd, but this homemade version tastes better.
Step 1: Whisk together sugar, egg whites, eggs in the large mixing bowl of a stand mixer. Make a double boiler by setting the large bowl over a saucepan filled with simmering water. Do not let the bottom of the mixing bowl touch the water.
Step 2: Whisk the whites and sugar constantly until sugar is dissolved and the mixture has thinned out and reaches a temperature of 165°F. The mixture will be thick and tacky at first, then thin out and appear frothy on top. Use an instant-read thermometer to check the temperature.
If you're making this recipe for the first time, I highly recommend using an instant-read thermometer to ensure you're hitting the right temperature. It's a simple check and ensures success.
Step 3: Once the sugar-egg mixture reaches the correct temperature place the bowl on the mixer stand.
Step 4: With the whisk attachment beat the meringue on high speed until it is cool to the touch, about 85F.
The meringue should be smooth and glossy with stiff peaks with the beater is lifted straight out of the bowl.
Step 5: Reduce the mixer to medium speed and add the butter 1-2 tablespoons at a time. Continue to add the butter until the buttercream looks like thick whipped cream. Beat in the vanilla extract.
Step 6: Whip 1/2 cup of lemon curd into the buttercream until all the curd is incorporated. The buttercream will be very light yellow.
Buttercream Tip: As the butter is added to the meringue the buttercream will look curdled part way through. This is okay - continue to beat in the butter and eventually the buttercream will take on a silky, cream texture.
The butter should be between 65-68 degrees F before adding it to the whipped egg whites. If the butter is too warm the buttercream won't set up and it will have a soupy consistency no matter how much butter you add. Trust me I know.
One thing I've learned over the years is that sometimes the amount of butter you use may vary. You may end up using less butter than the recipe calls for to reach the right consistency.
How to Store the Buttercream
If not using the Swiss meringue buttercream right away following these instructions for storing it.
- Room Temperature. Store the buttercream at room temperature for up to 1-2 days in an airtight container. The sugar in the buttercream keeps it from spoiling.
- Refrigerated. Store the buttercream in an airtight container for up to two weeks in the refrigerator.
- Freezer. Freeze the buttercream for up to 3 months in an freezer-safe airtight container. Thaw it out at room temperature on the counter, until it's about 70 degrees F. Once completely at room temperature, place it in the bowl of a stand mixer fitted with a paddle attachment and beat for 2-3 minutes until creamy again.
How to Use Lemon Buttercream
Use this lemon buttercream cakes and cupcakes, and even cookie fillings. This recipe makes 6 cups which is enough to frost a 9-inch cake or to frost 12-24 cupcakes depending on how much frosting you place on each cupcake.
Use it as the frosting or filling for the following recipes:
- Coconut Layer Cake. Coconut and lemon make a great pairing.
- Raspberry Cupcakes. Raspberry and lemon are a classic combination.
- Lemon Cupcakes. Lemon cupcakes with lemon buttercream taste absolutely delicious
Pro Tips for Making This Recipe
- It is essential to have a clean and dry bowl for whipping the egg whites. The egg whites cannot contain any egg yolk whatsoever. If the bowl is not completely clean or there is egg yolk in the egg whites, it prevents the meringue from setting up.
- This recipe uses large egg whites. If you're using different size eggs use a kitchen scale to weigh the egg whites.
- Eggs are easier to separate when cold, but egg whites whip up easier when closer to room temperature. I recommend separating the egg in advance. In addition, allowing the egg whites to sit gives them a chance to relax, which improves their elasticity during the whipping process.
- For best results use room temperature butter (65-68F). If the butter is too warm, the buttercream will be soupy and not set up properly. If that happens, chill the buttercream in the refrigerator for 15 minutes.
- It is entirely normal for the Swiss meringue buttercream (SMBC) to look soupy or curdled in the beginning after a portion of the butter has been added. That’s okay, just continue to whip it and it will soon firm up and become creamy.
If you make this delicious and creamy Lemon Swiss Meringue Buttercream please leave a rating and a comment below.
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Lemon Swiss Meringue Buttercream
Equipment
- Instant-read thermometer
Ingredients
Lemon Curd
- 1/2-3/4 cup Lemon Curd
Swiss Meringue Buttercream
- 5 large (150 grams) egg whites
- 1-1/4 cups (250 grams) granulated sugar
- 1/4 teaspoon kosher salt
- 30 tablespoons (424 grams) unsalted butter room temperature (65-68 degrees F)
- 1 teaspoon pure vanilla extract
Instructions
Lemon Curd
- Use this recipe for homemade Lemon Curd. You need less than half of the recipe, but the remainder can be stored in the refrigerator or frozen for up to a year.
- If making the lemon curd the same day, it will need at least 2 hours to chill in the refrigerator before adding it to the buttercream.
Lemon Swiss Meringue Buttercream
- Half fill a 3-quart or 4-quart saucepan with water and bring it to a simmer over high heat. Once it starts to simmer, reduce the heat to medium.
- Make sure the mixing bowl is clean and dry for whipping the egg whites. The egg whites cannot contain any egg yolk whatsoever. If the bowl is not completely clean or there is egg yolk in the egg whites, it prevents the meringue from setting up.
- Place the egg whites, sugar, and kosher salt in the bowl of a stand mixer and set it over the pan of simmering water. Do not allow the bottom of the pan to touch the water.
- Whisk until the mixture by hand until reaches 170°F then immediately put the bowl on the mixer stand, attach the whisk attachment, and whip at medium-high speed until the meringue mixture is cool (about 80-85°F).
- With the mixer on medium speed add the butter to the meringue 1-2 tablespoons at a time. About half-way through adding all the butter, the buttercream will begin to look curdled. Don’t worry it’s supposed to look like this. Continue to add the butter and eventually the buttercream will begin to look creamy and smooth, almost like thick whipped cream. You may need less than the full amount of butter to reach the desired consistency.
- Scrape down the sides and bottom of the bowl. Add 1/2 - 3/4 cup lemon curd to the buttercream and mix it in on medium speed and mix just until the lemon curd is mixed it. The buttercream will be very light yellow.
- Use the buttercream right away to frost and decorate your cake or cupcakes.
Storage
- The buttercream is good at room temperature for up to 2 days because of the amount of sugar which inhibits bacteria growth and the cooked egg whites. The buttercream can be refrigerated in an airtight container for up to 2 weeks. When ready to use, place in the bowl of a stand mixer and beat on medium speed for 2-3 minutes until it appears smooth and creamy.
- To freeze the buttercream place it in an airtight freezer safe container. It can be frozen up to 2 months. When ready to use the buttercream let it come to room temperature (68-70 degrees F) on the kitchen counter and then follow the directions above to restore its smooth and creamy texture.
Jeannette says
This turned out perfect!!!
Thank You!!
Cheryl Norris says
Hi Jeannette
I'm so glad you like this recipe. Thanks for trying it. What did you use the buttercream on?
Katie says
This was my first time making Swiss meringue buttercream AND my first time making one of your recipes. It turned out soooo much better than I anticipated. Thank you so much for the detailed instructions and photos. I can't wait to try more of your recipes. I saw that you have a blackberry and raspberry version of the SMBC and I'm curious if I can add any jam to the recipe in place of the curd? I was thinking of trying a spice cake with apple butter in the frosting where the lemon curd is.
Cheryl Norris says
Hi Katie
Thank you so much for trying my buttercream recipe and leaving this wonderful review. I'm glad the recipe turned out for you and that you found the detailed instructions helpful. For the other versions I use a fruit reduction. This method removes most of the water from the pureed fruit which allows for a more intense flavor but also reduces the risk of the buttercream splitting by adding too much liquid. I don't know how Swiss meringue would do if you added jam. I would start with a small amount, like 1/4 cup, and then if you want to add more add it 1 tablespoon at a time.
Liyana says
Super excited to make this! Is this recipe enough for a 3-layer cake with a little bit of piping work?
Cheryl Norris says
Hi Liyanna
To have enough for 3 layers and decorations I suggest increasing the recipe by 50 percent.
Carol Macri says
How does this buttercream take a color? I need to make a turquoise icing with it. Will it be OK?
Cheryl Norris says
Hi Carol
I haven't tried adding color to this icing, since it's already yellow from the lemon curd. You may not get the shade of turquoise you want. I suggest trying my Swiss meringue buttercream recipe if you want to add color.
Let me know if this answers your question.
Carol Macri says
Thank you for such a quick reply. I was thinking since it was yellow it might turn the color green. Yes, the Swiss meringue buttercream is what i usually use but was asked for an all lemon cake with lemon filling and lemon icing. I think I’ll do the lemon buttercream first and the Swiss meringue over that with the color. That should work. Thanks again.