True buttercream does not have powdered sugar, a common ingredient in most frostings. It's made by making a meringue from egg whites and combining it with a cooked syrup and, of course, a truckload of butter. It's not super sweet, but is smooth and light and amazing. I've noticed that many cupcake shops say their frosting is buttercream, but very few places actually use true buttercream. There's a tiny little cupcake shop in downtown Seattle called Yellow Leaf that has lots of different interesting and delicious flavors of buttercream.
I made this tonight for cupcakes for a church event, but neglected to take pictures of any of the cupcakes. Good thing I had a little dollop left for a graham cracker. It made for the perfect snack since I mostly care about the frosting anyway.
A few notes on buttercream:
- You'll need a candy thermometer to keep track of the temperature of the syrup.
- If the mixture looks a little soupy while mixing, don't fret, it will come together in the end.
- The buttercream is done when it thickens slightly and the soupiness disappears.
- Although the recipe calls for unsalted butter, you can use salted if you'd like. I like the sweet-and-salty combo so I like to use half salted and half unsalted butter.
- Buttercream can be made 1 week ahead and chilled, covered, or 1 month ahead and frozen. Bring to room temperature (do not use a microwave) and beat with an electric mixer before using.
- 4 large egg whites at room temperature
- 1/2 teaspoon salt
- 1 1/4 cups sugar
- 1/2 cup water
- 1/2 teaspoon fresh lemon juice
- 3 sticks (1 1/2 cups) unsalted butter, cut into tablespoon pieces and softened
- 1 1/2 teaspoons vanilla extract (or almond or coconut extract)
Combine egg whites and salt in bowl of a standing electric mixer with whisk attachment or other large bowl.
Stir together sugar and water in a small heavy saucepan and bring to a boil over moderately high heat, stirring until sugar is dissolved.
When syrup reaches a boil, start beating whites with electric mixer at medium-high speed.
Once whites are frothy, add lemon juice and beat at medium speed until they just hold soft peaks. (Do not beat again until sugar syrup is ready—see below.)
Meanwhile, put thermometer into sugar syrup and continue boiling, without stirring, until it reaches soft-ball stage (238–242°F).
Immediately remove from heat and slowly pour hot syrup in a thin stream down side of bowl into egg whites, beating constantly at high speed.
Beat meringue, scraping down bowl with a rubber spatula, until meringue is cool to the touch, about 6 minutes or longer. (It's important that meringue is fully cooled before proceeding.)
With mixer at medium speed, gradually add butter 1 piece at a time, beating well after each addition until incorporated.
(If meringue is too warm and buttercream looks soupy after some butter is added, chill bottom of bowl in a larger bowl filled with ice and cold water for a few seconds before continuing to beat in remaining butter.)
Continue beating until buttercream is smooth.
NOTE: Mixture may look curdled before all butter is added, but will come back together before beating is finished.
Add vanilla extract and beat 1 minute more.