This faux lemon Swiss meringue buttercream has a silky smooth, ultra-creamy consistency and is flavored with lemon curd. It's made with pasteurized egg whites and powdered sugar, so it's easier to make than classic SMBC but just as stable and delicious on all your favorite layer cakes and cupcakes.
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Why You'll Love This Recipe
- Faux method- Traditional Swiss meringue buttercream starts by dissolving granulated sugar in egg whites over a double boiler (Bain-marie). The gentle heat cooks the egg whites, making them safe to eat before whipping the mixture into a stiff meringue. For faux Swiss meringue buttercream, the trick is using pasteurized egg whites that are already heat-treated to kill bacteria. The powdered sugar dissolves into the egg whites seamlessly, so you don't need a double boiler! I also used this method to make chocolate Swiss meringue buttercream, and it worked perfectly.
- Lemon curd for flavor- I experimented using fresh lemon juice and lemon zest to flavor this buttercream, but it made it curdle. Lemon curd gave it a deliciously bright flavor that's so much better than lemon extract and kept the consistency perfectly creamy.
- Super smooth texture- This buttercream is super rich, creamy, and smooth, plus it doesn't crust like American buttercream. It's the perfect frosting to use when you're craving something a little less sweet.
Ingredient Notes
- This lemon Swiss meringue buttercream is made with pasteurized egg whites, which are heated and rapidly cooled to eliminate harmful bacteria. Many everyday ingredients are pasteurized, like milk and juice. Using pasteurized egg whites means there is no need to heat the mixture over a double boiler like you would with traditional Swiss meringue buttercream. You can find them in the egg section of most grocery stores. Just make sure the carton is clearly labeled "pasteurized."
- There is no need to sift the powdered sugar before mixing it with the egg whites. It dissolves easily as the meringue whips, resulting in a smooth buttercream.
- I prefer using salted butter for this lemon buttercream because a little salt adds depth and helps balance the sweetness and tangy citrus. Cut the butter into tablespoon-size pieces while it is still cold, then let it soften fully to room temperature before adding it to the meringue. It should be soft enough for you to press your finger into, but it shouldn't look melted or greasy. Butter that is too cold will not emulsify properly and can cause the frosting to look curdled or chunky.
- For the best, most intense lemon flavor, I highly recommend making lemon curd from scratch. Store-bought does work in a pinch, but most brands just don't have the tartness and brightness of homemade lemon curd. I recommend Trader Joe's if you go the store-bought route! Note that lemon curd varies in thickness and can affect the texture of your frosting.
For the full list of ingredients and measurements, see the recipe card below.
Expert Baking Tips
- Wipe down your equipment. Before you begin, make sure your mixing bowl and attachments are completely clean and dry. Even a small amount of grease can prevent the egg whites from whipping properly. You can also chill the bowl in the refrigerator or freezer for about 30 minutes, which helps the egg whites whip up more quickly.
- Use room temperature butter. If the butter is too cold, the frosting will curdle. If it's too warm, the buttercream will be thin and soupy. If that happens, chill the buttercream in the refrigerator for 15 minutes before adding the lemon curd.
- Just keep mixing! It's normal for the buttercream to look a little soupy as you begin to add the butter, but that's totally normal. Just keep mixing and it should come together. Also, if you test your buttercream and it still tastes like butter, keep mixing it. The final product should be light and sweet.
Step by Step Instructions
Step 1: Add the powdered sugar and pasteurized egg whites to the bowl of a stand mixer and mix on low speed with the whisk attachment for about 30 seconds to combine. This helps prevent the powdered sugar from flying out of the bowl.
Step 2: Increase the mixer to medium-high speed and whip until the mixture is thick and bright white.
Ideally, the meringue will form stiff peaks with slightly curled tips. If the peaks are a little looser, that's completely fine. Pasteurized egg whites don't whip quite as firmly as fresh ones. As long as the mixture is opaque, glossy, and falls from the whisk in very slow ribbons, you're ready for the next step.
Step 3: With the mixer running on medium speed, add the softened butter one tablespoon at a time, allowing each addition to fully incorporate before adding the next. Stop occasionally to scrape down the sides and bottom of the bowl. This process takes about 8-10 minutes, but adding the butter slowly is key to creating a smooth, stable buttercream.
It's very common for the buttercream to look curdled or broken partway through, especially if the butter was slightly cool. Don't worry; keep mixing. As the butter warms, the frosting will come together into a silky, creamy texture.
Step 4: Next, add the vanilla extract and lemon curd, then mix until combined. If you want to color your buttercream, I recommend adding gel food coloring here.
Once all the ingredients are fully combined and the frosting is fluffy, switch your whisk for the paddle attachment. Run the mixer on low to make the frosting super smooth and pop air bubbles. This makes it much easier to spread on cakes!
Fixing Curdled Buttercream
If your frosting curdles after adding the butter, don't worry. It's an easy fix! Remove about ยผ cup of frosting from the bowl and microwave it for 20 seconds or until it's barely melted. Add it back into the rest of the buttercream and continue mixing to smooth everything out.
Storage
The lemon Swiss meringue buttercream can be stored in an airtight container in the refrigerator for up to 2 weeks. Let it reach room temperature before using and mix well to make the consistency smooth again.
Cakes frosted with this buttercream can last in the fridge for up to a week or in the freezer for 1 month. I highly recommend trying this frosting on my lemon poppyseed cake or lemon olive oil cupcakes!
More Frosting Recipes to Try
๐ Recipe
Lemon Swiss Meringue Buttercream (Faux Method)
Equipment
- 1 5-quart stand mixer with the whisk and paddle attachments
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Ingredients
- 113 grams pasteurized egg whites cold
- 450 grams powdered sugar
- 453 grams salted butter room temperature
- 1 teaspoon vanilla extract
- 112 grams lemon curd homemade or store-bought
Instructions
- Add the pasteurized egg whites and powdered sugar to the bowl of a stand mixer fitted with the whisk attachment. Mix on low speed for about 30 seconds, just until the sugar is moistened so there's no risk of it flying out of the bowl.113 grams pasteurized egg whites, 450 grams powdered sugar
- Increase the mixer speed to medium-high and whip for 8-10 minutes, until the mixture becomes thick, bright white, and glossy. The meringue should hold its shape when you lift the whisk, with soft peaks that gently bend at the tips. It does not need to be completely stiff to work. As long as it falls off the whisk in slow, thick ribbons, it's good to go.
- Reduce the mixer speed to low and begin adding the softened salted butter, one tablespoon at a time. Allow each addition to fully blend in before adding the next. This step takes about 8-10 minutes total. The buttercream may look loose or curdled along the way; keep mixing and it will smooth out.453 grams salted butter
- Once all the butter is incorporated, stop the mixer and switch to the paddle attachment. Add the vanilla extract and lemon curd, then mix on medium-low speed until the buttercream is silky smooth and most of the air bubbles are knocked out.1 teaspoon vanilla extract, 112 grams lemon curd
- Transfer the frosting to a piping bag and use to decorate cakes, cupcakes, or cookies!
Notes
- Storage: Store the buttercream in an airtight container in the refrigerator for up to 1 week. Let it come fully to room temperature before using, then re-mix until smooth.
- Make ahead: This buttercream can be made several days in advance. After chilling, rewhip briefly with the paddle attachment to restore its silky texture.
- Freezing: The buttercream freezes well for up to 2 months. Thaw overnight in the refrigerator, then bring to room temperature and re-mix until smooth before using.
- Flavor adjustments: Add more lemon curd gradually to taste, but avoid adding too much at once or the buttercream might get thin and soupy.
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