Kathy calls me the Buttercream Whisperer. Silly I know, but it does speak volumes about how luscious a well made meringue-based buttercream can be. Most all of us grew up on "buttercream" that was made by beating butter and powdered sugar together. And although that frosting is a fun trip down memory lane, I much prefer the slightly-more-technical, but oh-so-velvety meringue versions. Made up of 3 simple ingredients, this style of buttercream is delicate, delicious and can be flavored a variety of ways. For this recipe, we are going to focus on Swiss Meringue Buttercream. Don't be afraid of the name or the lengthy instructions. And don't be confused by the many minor variations between recipes like the ratio of sugar to egg whites to butter, how hot you heat the egg white/sugar mixture, etc. The important take-away is the technique. Trust me, great buttercream is easy to master.
Wipe the bowl and whip attachment of an electric mixer with a paper towel and lemon juice or vinegar. This will remove any trace amounts of grease.
Add egg whites and sugar to the bowl. Stir to combine.
Place the bowl over a pot of simmering water (a bain marie). Stir the egg white/sugar mixture gently but constantly until the mixture reaches 140˚F - 160˚F.
There is a pretty big window for success since the sugar will melt and raise the coagulation temperature of the egg whites. However you must pay attention, keep the sides of the bowl scraped clean and keep the mixture moving. If you leave this mixture unattended you could end up with scrambled egg whites. For your first attempt, use an instant read thermometer. However, at the correct temperature, the mixture will be hot, the sugar will be dissolved, and the mixture will feel completely smooth when rubbed between your fingertips.
Remove the bowl from the heat and attach to the mixer fitted with the whisk attachment. Whisk the mixture on medium high speed until a thick, glossy meringue forms. Turn the speed to medium low and continue mixing until the mixture is completely cool, about 10 minutes.
You can test this by touching the bottom of the bowl or turning off the maching and putting your finger in the middle of the meringue.
Do not begin adding room temperature butter until the bottom of the bowl feels neutral, and not warm.
Continue to whip the mixture (with the whisk or paddle attachment) while adding room temperature butter slowly; a few tablespoons at a time.
Now this is when the magic happens. The meringue will naturally deflate when you begin to add butter. For a period of time, it will look like very softly whipped cream and will be quite runny. As you continue to add butter, you will notice the edges take a on a grainy, curdled texture. This is the awkward stage just before the frosting comes together. It looks broken and hopeless, but you are actually getting close. Keep adding butter and eventually the mixture will transform into a fluffy, shiny, satin-like frosting that is quite thick.
Add vanilla and salt to taste.
This buttercream can be flavored almost endlessly. Add citrus zest, ground spices, liqueurs....don't be afraid to get creative; just add the flavorings at the very end.
Notes, notes and more notes. There is a lot to say about buttercream.
- **It is essential to have your butter at room temperature. Buttercream does not do well at extremes. If the butter is too cold, the mixture will not come together and will always look broken and curdled. If the butter is too warm, it will take a lot more of it to make the mixture turn, resulting in a dense, overly buttery frosting.
- You always want to eat buttercream at room temperature. This may mean planning ahead and giving your baked goods time to come up to temperature. Cold buttercream has the texture of, well, cold butter.
- Buttercream can be stored at room temperature for 3-5 days. If you want to refrigerate or freeze extra buttercream, be sure to bring it to room temperature before working with it again.
- *In order to whip properly, the egg whites must be completely grease free. Make sure your utensils are clean and the whites are not contaminated by any bits of yolk. Read more about separating eggs cleanly and why it matters.