Today I have for you our favorite cake filling recipe: Swiss Meringue Buttercream or SMBC!
Swiss Meringue buttercream is our first choice of frosting for cupcakes and cakes, because it’s very stable, has a long shelf life and is wonderfully fluffy. By heating our meringue to 70 degees Celsius, we make sure to pasteurize the egg whites, so it can be enjoyed by everyone!
While making SMBC can be a little tricky at first, once you master the temperatures of the ingredients, it should come together really nicely. I do recommend using a thermometer while making this buttercream – you can find inexpensive ones in most household stores.
Recipe for Swiss Meringue Buttercream
- 250 ml / 1 cup egg whites (approx. 8 eggs, we tend to use pre-bought egg whites in a carton)
- 300 g / 1.5 cups sugar
- 1/2 tsp salt
- 500 g / 4.5 sticks soft butter, at room temp (at least 22 degrees Celsius)
Place sugar, egg whites and salt in a large bowl and heat to 70 C / 158 F over a gently simmering water bath. Stir and scrape the edges with a rubber spatula every 2 minutes or so – you don’t want the egg white to coagulate. Use a thermometer to measure the temperature.
As soon as the mixture hits the right temperature, transfer it to a clean mixer bowl immediately. Beat it with a whisk on medium-high speed, until you have a stiff meringue. Keep beating the meringue until it has cooled down below 30 C / 86 F.
If using a stand mixer, swap the whisk attachment for a mixing paddle. Turn the mixer on the lowest speed (this is very important!) and add the butter slowly, one heaped tablespoon at a time. Make sure your butter is really soft – you should be able to cut through it with a knife effortlessly. We must ensure that the meringue and the butter are at equal temperatures – that will make the water-based egg white and the fat-based butter emulsify (mix together) more quickly, while losing a minimum of the volume of the air bubbles in the meringue.
Then comes the easy part: Sit back and wait! Keep the mixer on the lowest setting. Don’t panic if the mixture looks liquid or curdled. The buttercream will go through what I call the “cottage cheese” stage. And soon afterwards, it should emulsify beautifully and look like a fluffy buttercream.
Once it has reached this stage, you can turn the mixer on high again and beat your buttercream on medium-high for 5-10 minutes, to incorporate some more air. You will notice it will get a lot lighter in color.
Your buttercream is done! Now you can add color and flavors of your choice.
The moment when SMBC emulsifies… it’s like magic, every time!
Here are some flavoring ideas for Swiss Meringue buttercream:
If you make SMBC, please leave a comment!
Thanks and happy baking,