This is only the second time I’ve ventured into the Italian buttercream frostings, a delicious confection for frosting cakes. Previously I made a malt buttercream for the chocolate malt layer cake: first the egg whites are whipped then hot syrup is added to the whipped egg whites.
I have discovered Italian meringues are well worth the trouble because the so-called “quick” or American buttercreams–whipping butter and sugar– are way too sweet. It’s true that when chilled, the Italian buttercream turns stiff into butter, but at room temperature, it is deliciously light, airy, and doesn’t seem to be as sweet even though a similar amount of sugar has been added to it.
This chocolate buttercream frosting is adapted from Ina Garten’s recipe. It’s different from the traditional method in that the egg whites, sugar, salt, and cream of tartar are heated and then whipped. The addition of espresso coffee and rum intensify the chocolate flavors so I recommend adding them to the frosting. This recipe makes more than 4 cups of frosting because, after frosting 3 seven-inch round layers I had 3 cups left over.
Chocolate Buttercream Frosting
Prep time: 15 minutes
Active time: 60 minutes (includes frosting the cake)
Yield: 4 cups
1 pound dark chocolate (at least 65% cacao)
12 ounces semi-sweet chocolate
3/4 cup egg whites, room temperature
1 1/2 cups superfine sugar
1/4 teaspoon cream of tartar
3/4 teaspoon salt
1 1/2 pounds unsalted butter, room temperature
3 teaspoons vanilla
3 teaspoons instant espresso powder dissolved in 1 1/2 teaspoons water
3 tablespoons dark rum
Set a large pot filled one-third full of water. Heat it to simmering on the stove. Meanwhile, chop the chocolates and put them in a heat-proof bowl over the simmering water. Don’t let the bowl touch the water. Stir the chocolates occasionally to melt. As the melting progresses, stir constantly so all the pieces melt and the chocolate becomes smooth. Set aside. Don’t turn off the heat.
In the bowl of a stand mixer fitted with the whisk attachment, add the egg whites, sugar, cream of tartar, and salt. Mix until frothy. Scrape the mixture into another heat-proof bowl and set this over the simmering water. Stir constantly, warming the egg whites and dissolving the sugar and salt, about 3-5 minutes. Test the mixture by rubbing some of it between your fingers to be sure there is no sugar grit remaining. Scrape back into the mixing bowl.
Cake Baker’s Note: I rinsed out the mixing bowl before putting back the warmed egg white mixture.
Whip the egg whites on high speed until the meringue turns glossy and stiff peaks form, about 5 minutes. Scrape down the bowl. By now the bowl should feel cool to the touch.
Reduce to medium speed. Add the butter 1 tablespoon at a time. The frosting will turn yellow and at times will look curdled. The volume will also deflate. Keep going, this is normal. Scrape down the sides.
Add the melted chocolate, vanilla, espresso, and rum. Beat on medium speed until the chocolate mixture is blended. If the buttercream seems too soft, cool the mixture then beat it again. At the French Culinary Institute in NY, the chef put the bowl of buttercream in an ice water bath.
Frost the cake.