When I first started making cakes, I knew nothing about buttercream/frosting/icing and just how many different types there are. My first batches of cupcakes were frosted with *cringes* those cans from the grocery store of Pilsbury and Betty Crocker frosting. I hate to admit that I loved it then, but I won't even let that stuff touch my lips anymore. Then for a little while I was making American Buttercream (powdered sugar + butter), it was simple and typically found on pastries at bakeries in my area, so very relatable. My problem with American BC was that it wasn't easy to frost cakes with and I often found it to be sickeningly sweet due to how much powdered sugar is needed to make it stiffen. Now the only type of frosting I make and use on a regular basis is Swiss Meringue Buttercream (often referred to as SMBC). It's just as light and fluffy as those chemical filled cans with a million times more flavor, but not too much sweetness, and probably a million less carcinogens. And it is SO simple to make with only 3 ingredients that are usually on hand in my house--sugar, egg whites, and unsalted butter!
My first experience with meringue buttercreams was a couple of years ago when I tried another baker's cake in a competition I had entered in. I was completely amazed by the deliciously light flavor and texture paired with the cake. When I asked what kind of frosting they used, the baker responded with "Italian Meringue Buttercream". I immediately went home and researched what this mythical substance was made of and how I could recreate it for myself. Upon doing some digging and research I found that there were actually a few methods for making the meringue besides the "Italian" method. The Italian method involves heating a sugar syrup and then whisking it into the egg whites while it is boiling hot. Not being a huge fan of working with hot sugar (a handful of small burns was enough for me at this point), I found that the Swiss method of meringue seemed much safer while still achieving the look and texture I was going for!
The Swiss method for meringue involves heating the sugar and egg whites together in a double boiler until all of the sugar melts and forms a nice thick syrup with the egg whites. Heating the egg whites also ensures that they are pasteurized and that any bacteria has been removed. After the sugar-egg white syrup has been made, it gets removed from the double boiler and whipped (hopefully in a stand mixer, GO YOU if you've got the arm strength to do it manually) until you reach nice stiff glossy peaks.
As the meringue is being whipped you'll want to chop up the sticks of unsalted butter into "bite-sized" or about 1 tbsp sized chunks. One of the first recipes I read suggested that they be "bite-sized" pieces and I nearly hurled imagining biting into a stick of butter, but it's actually a very accurate size description. You can chop them up and pile them into a bowl and stick that bowl back into the fridge if the meringue isn't stiff enough yet. Basically you want the meringue and the butter to both be as chilled as possible when you go to combine them. The meringue will cool down as it gets whipped and should be around room temp but the time you've reached stiff peaks. If the meringue is still warm enough that you fear it will melt the butter, let it sit to cool for a little longer before you start to incorporate the chunks. You can check the temp by placing your palm on the bottom of the mixer bowl.
This is the part where everything can get really scary. If the meringue or the butter are too warm when you start to combine them you will end up with a soupy curdled-looking mess. BUUTTTT even if you get this mess, the buttercream can still be saved!! My first attempt did not go so well because I did not realize that this step could be part of the process and not just an utter failure on my part. I ended up dumping out my first batch of SMBC because it looked absolutely disgusting and I had it going on my stand mixer for WAAAY longer than any recipe talked about. If only I had researched more and seen that all I needed to do was chill it and whip it for a bit longer. My two rules of SMBC are now; make sure it's completely chilled, and JUST KEEP MIXING. Seriously, I don't think it's possible overmix the buttercream once you've combined the meringue and the butter so if it's looking soupy, CHILL and JUST KEEP MIXING!
The end product should be a delightfully creamy and rich yet still light and fluffy buttercream. It is absolutely AMAZING for piping and decorating cakes with. It holds up in warm temps longer than any buttercream I've ever seen and it stiffens up PERFECTLY when refrigerated, no crust or crispy bits involved! It's also very easy to flavor and holds gel food coloring wonderfully, two problems that I've often encountered with an American Buttercream. Following is the full list of steps with ingredients needed to make enough buttercream to generously frost a 3-4 layer 9" cake. I can't really say that this is "my recipe" but more-so my preferred ratio for making the SMBC. You can experiment with more/less meringue or butter to find what works for you, but for me I like the BC to be VERY light and fluffy so that's what you should get if you follow this recipe!
SWISS MERINGUE BUTTERCREAM
If you want to color the SMBC I recommend only using gel food color. The color will be much more vivid as it sets in the buttercream so start at a pastel tone and add color slowly from there.
To make a chocolate SMBC, melt down 1/2 c. to 1 c. your favorite chocolate and mix it in once it has cooled but is still liquid. (I highly recommend using a chocolate that is meant for melting and flows nicely when melted. I found that thicker, cheaper chocolates can harden and leave unwanted hard chunks in your BC.)
PLEASE let me know if you try this recipe and how it goes for you! I'd love to hear any and all feedback and I hope you enjoy this buttercream just as much as I do!