Mocha Buttercream from The Essential Baker by Carol Bloom
Makes enough to cover and fill a 9-inch cake
2 extra-large eggs, at room temperature
2 extra-large egg yolks, at room temperature
1/4 cup granulated sugar
1 1/4 cups granulated sugar
1/2 cup water
1/4 teaspoon cream of tartar
1 pound (2 cups, 4 sticks) unsalted butter, softened
6 ounces bittersweet chocolate, very finely chopped, melted over a double boiler and cooled to room temperature
2 teaspoons instant espresso powder
1 tablespoon water
In a small sauce pan fitted with a candy Thermometer, bring the 1 1/4 cups sugar, water and cream of tartar to a boil over medium-high heat. If any of the sugar crystals get onto the side of the pan, be sure to wipe them down with a wet clean pastry brush. The sugar needs to cook until it hits 242° F on the thermometer.
This takes several minutes. While that is boiling, Place the eggs, egg yolks and sugar in the bowl of your stand mixer and whip on medium speed until they are thick, pale in color and hold a ribbon when the beater is lifted. Once the sugar syrup has reached its temperature of 242° F, then slowly pour it into the bowl of whipped egg yolks while the beater is going on slow. Be sure to pour it along the bowl so that the hot syrup doesn’t hit the beater and splatter! Allow the eggs and sugar mixture to beat on medium high speed until the eggs have cooled, about 8 minutes.
Add the butter 2 tablespoons at a time. The buttercream will go through a stage that looks soupy and curdled, but continue to add all of the butter and it will come together.
The finished buttercream will be smooth and silky.
Add a tablespoon of water to the espresso powder and dissolve. Add the melted and cooled chocolate to the buttercream. Mix to combine and decorate your cake.
The buttercream will freeze if you have any left, wrapped really well in plastic. Just allow it to come bake to room temperature and whisk it on low speed to smooth it out.