Rich, moist chocolate cupcakes are filled with a rich pistachio-chocolate ganache and topped with a luxurious salted pistachio buttercream. These cupcakes are perfect for special occasions and when you need something sweet that is out of the ordinary. This recipe calls for a specialty ingredient - pistachio butter. You'll need one 8 oz. jar to make this recipe. For the chopped pistachios that go in the ganache filling and garnish, use pistachios that have already been shelled, roasted, and salted, such as Wonderful brand (linked in blog post).
Preheat oven to 350°F. Line cupcake tins with 24 paper liners.
Using an electric mixer beat the butter and sugar together in a large bowl until light and creamy, about 5 minutes. Add the eggs; beat again until lightened in color. Add the cocoa, baking soda, vanilla extract and salt; mix well.
Beat in the flour in 3 additions alternately with the sour cream, begin and end with flour.
Add the hot coffee at the end and mix until a smooth batter forms. Divide the batter between the cupcake liners, about 3/4 full.
Bake the cupcakes for 20-22 minutes, or a toothpick tester comes out clean. The tops of the cupcakes should be well risen but flat on top. Let cool completely on a wire rack before filling and frosting.
Pistachio chocolate ganache
Combine the chocolate, cream, and pistachio butter in a large microwave-safe bowl. Heat at 100% power for 1 minute. Let stand for 1 minute, then whisk together until a smooth shiny ganache forms. Fold in the chopped pistachios. Transfer the ganache to a disposable piping bag.
Cut a divot into the tops of each cupcake, deep enough to hold about 1 1/2 tablespoons of the ganache filling. (Or, if you have a cupcake corer, now’s the time to use it!). Pipe the ganache into the centers of each cupcake. Set aside while you prepare the buttercream.
Pistachio buttercream
In the bowl of a stand mixer fitted with a whisk attachment, combine the butter and pistachio butter. Mix until creamy and well combined. Add the confectioners’ sugar and salt. Beat on low speed until the mixture comes together – it will be thick.
Add in the heavy cream and beat on high speed until fluffy and lightened in color. Add the green food color, if using. Mix well on high speed.
Transfer the buttercream to a piping bag fitted with a large closed decorator star tip. Working one at a time, pipe a swirl onto a cupcake, then immediately garnish with roasted salted chopped pistachios.
Store cupcakes at room temperature in an air tight cupcake keeper for up to 3 days, or store in the refrigerator to extend shelf life. Bring to room temperature before serving.
Notes
Pistachio Butter: Try to find pistachio butter with just one ingredient: pistachios. However, it's still okay to use pistachio butter with a little added salt and sugar. Natural pistachio butter will settle in the jar, so give it a good stir before using it in this recipe. Pistachio Butter vs Pistachio Paste: Pistachio butter is slightly different than pistachio paste. The butter is usually thicker than the paste and usually does not have sweeteners or additives. The paste, unlike the butter, may have additives such as sugar, powdered milk, oils, and emulsifiers. You can use pistachio paste, but you may need less confectioners' sugar in the buttercream. portion of this recipe.Ganache Filling: If you enjoy these cupcakes right after they've been filled and frosted, the ganache center will be soft and loose. Over time, the ganache will firm to a soft truffle-like setting, which is also quite nice.