Swiss Meringue Buttercream

Professional Tips for Making Swiss Meringue Buttercream

• Adding the salt to meringue add stability. Most recipes call for the salt to be added in at the end, but I like to make my ingredients work for me. Adding the salt to the meringue before cooking will stabilize the meringue and add flavor. And now you are baking like a professional chef too.
• Know its limits. It is the most stable when refrigerated but tastes the best at room temperature. If possible, I allow the whole cake to sit at room temperature for at least 2 hours prior to serving. You can also slice it cold then allow it to sit to ensure perfect slices.
• Weigh ingredients for the best results. There can be a 30% difference in the weight of one egg white depending on the size of the egg yolk. This means that the resulting meringue will be more or less stable depending on the ratio of egg white to sugar. For the average baker this does not matter, but if you are going to entrust a wedding cake to this buttercream, weigh your ingredients.
• People stress too much about fat in meringues. Here is the real talk: as long as there are no visible yolks in the whites and your bowl feels clean, then you are fine. Wiping out your bowl with vinegar is unnecessary and will impact the flavor. If your meringue is not whipping up, add cream of tartar by the teaspoon until it does. If you can taste it in the final meringue, then start again, but you probably won’t have to. Life is too short to stress about meringue.

Ingredients Needed

• Egg whites: Carton egg whites will not produce a stable meringue. I only use separated eggs for this recipe. Use the yolks in the best chocolate ice cream or hot chocolate. Try your best to keep the egg whites free from yolks, but don’t stress too much. As long as there are no visible yolks, you’re fine.
• Granulated sugar: Try to use extra fine sugar, which will help eliminate the possibility of a gritty meringue. If all you have is regular granulated sugar, don’t stress, it’ll be fine.
• Kosher Salt: Kosher salt is coarser than table salt and thus less salty per teaspoon. The added salt will stabilize the meringue and temper the sweetness just a enough.
• Butter: I use unsalted butter for all baking but especially in this recipe. Butter is one of the prominent flavors, so choose a high quality butter you enjoy. If you are trying to make a white buttercream, choose the whitest butter possible! This will probably have the lowest fat percentage as well.
• Vanilla: I use vanilla extract as the flavor in this recipe but you could use a combination of vanilla beans and extract or vanilla bean paste. Vanilla will color the buttercream, so omit it or use imitation vanilla instead.  

Variations

• Color Swiss Meringue Buttercream: Swiss meringue colors best with powdered food colorings especially if you want vivid, saturated colors. The amount of gel food coloring needed will loosen the buttercream and eventually make it very unstable. Gel is the easiest option if you want lighter, more pastel hues. Liquid food colors are not a great option.
• Change the flavor: Use different extracts and add a little bit and taste as you go. Add ½ cup nut butter, ½ cup lemon curd, ¾ cup caramel sauce, and up to ¾ cup fruit preserves. The buttercream will only take so much acidity, so add preserves, jams and jellies bit by bit. Obviously strain them if you want smooth buttercream. You can make it chocolate by adding 200 g (7 oz) melted dark chocolate.  

Why use Swiss Meringue Buttercream?

• SMB is the most stable buttercream. It has more sugar than Italian meringue buttercream, which makes it ever so slightly more stable.  This means that if your buttercream needs to be in a warm room for an hour or two, you will be alright!
• The meringue makes the frosting more structurally sound. IMB or SMB are perfect for those extravagant layer cakes or cakes with a looser filling. The butter and meringue set solid in the refrigerator, so you can tier up! Just be sure to use cake straws or wooden dowels to support the additional layers. Even the best SMB will crush under the weight of two tiers of cake, filling and buttercream. It’s not magic!
• Faster than any other meringue based buttercream!
• Can be made entirely by hand. Unlike Italian Meringue, where I do not suggest making it without the protection of a stand mixer, SMB can safely be done with a hand mixer.
• It’s less sweet! The meringue cuts the sweetness of traditional American vanilla buttercream. In American frostings you have to use confectioner’s sugar for the stability, but the meringue gives you all the perks without the cloying sweetness.

How to Make

Use these instructions to make the perfect vanilla Swiss meringue buttercream every time! Further details and measurements can be found in the recipe card below.

Beforehand: I take my cubed butter out of the refrigerator when I start the meringue. This will allow it to achieve the perfect point of soft, pliable but still just a little cold. You should be able to squish it easily with your finger.

Step 1: Set up a bain marie or water bath. Heat about an inch of water up in a medium sauce pot until it is just about simmering.

Step 2: Whisk together egg whites, sugar and salt in the stand mixer bowl. Then place bowl over top of simmering water and continue whisking constantly. Cook the whites and sugar just until it reaches 130°F on an instant read thermometer or until the sugar has dissolved and the mixture is warm to the touch. The meringue will have started to gain a bit of volume and feel lighter at this point as well.

Step 3: Move the bowl to your stand mixer and fit with the whisk attachment. Be careful and use a towel because the bowl will be hot if you have a gas burner! Beat on high speed until the meringue reaches stiff peaks and cools slightly.

Step 4: Switch to the paddle attachment and then add all the butter. Beat on medium until all the butter works itself into the meringue and a silky smooth buttercream forms.

Step 5: Once your buttercream comes together, switch back to the whisk and beat it up until it is light and fluffy! Frost away or store in the refrigerator or freezer.