Lemon Swiss Meringue Buttercream

5 from 3 votes

This tart and creamy Lemon Buttercream frosting is an intensely fruity and flavorful version of my Swiss meringue buttercream. It's ultra-creamy, stable (meaning it will hold its shape), light, and fluffy. It's made with a combination of Swiss meringue, butter, and homemade lemon curd.

Prep Time20

Cook Time10

Cooling Time10

Total Time40

Course: Dessert

Cuisine: Swiss

Servings: cups

Calories: 661kcal

Author: Cheryl Norris

Equipment

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.

Notes

Egg Whites: Use the egg whites leftover from making the lemon curd for the buttercream. Separate the eggs while the eggs are still cold because the yolk is less likely to break.

Store Leftover Egg Yolks: If using store-bought lemon curd, the yolks will keep for up to four days in the refrigerator in an airtight container. To keep the egg yolks from drying out, add enough cold water to the container to just cover the tops of the egg yolks. Drain them off before using.

Nutrition