For the Ganache Filling:
2 ounces bittersweet chocolate, finely chopped
¼ cup heavy cream
1 tablespoon powdered sugar

For the Cupcakes:
3 ounces bittersweet chocolate, finely chopped
⅓ cup Dutch-processed cocoa powder
¾ cup hot coffee
¾ cup bread flour
¾ cup granulated sugar
½ teaspoon salt
½ teaspoon baking soda
6 tablespoons vegetable oil
2 eggs
2 teaspoons white vinegar
1 teaspoon vanilla extract

For the Frosting:
1¼ cups unsalted butter, at room temperature
1 cup powdered sugar
¾ cup Dutch-processed cocoa powder
Pinch of salt
¾ cup light corn syrup
1 teaspoon vanilla extract
8 ounces chocolate (milk, semisweet or dark), melted and cooled

1. Make the Ganache Filling: Place the chopped chocolate, heavy cream and powdered sugar in a small bowl. Heat in the microwave on high power until the mixture is warm to the touch, 20 to 30 seconds. Whisk until smooth, then refrigerate until just barely chilled, no longer than 30 minutes.
2. Make the Cupcakes: Preheat oven to 350 degrees F. Line a standard-size muffin pan with liners. Place the chopped chocolate and cocoa powder in a medium bowl. Pour the hot coffee over the mixture and whisk until smooth. Refrigerate mixture for 20 minutes.
3. Meanwhile, whisk together the flour, sugar, salt and baking soda in a medium bowl; set aside.
4. Whisk the oil, eggs, vinegar and vanilla extract into the cooled chocolate mixture until smooth. Add the flour mixture and whisk until smooth.
5. Divide the batter evenly between the muffin pan cups. Place one slightly rounded teaspoon of ganache filling on top of each cupcake. Bake until the cupcakes are set and just firm to the touch, 17 to 19 minutes. Cool the cupcakes in the pan on a wire rack for 10 minutes, then remove the cupcakes from the pan and place on the wire rack to cool completely, about 1 hour.
6. Make the Frosting: In a food processor, process the butter, sugar, cocoa powder and salt until smooth, about 30 seconds, scraping the sides of the bowl as needed. Add the corn syrup and vanilla extract and process until just combined, 5 to 10 seconds. Scrape the sides of the bowl, then add the chocolate and pulse until smooth and creamy, 10 to 15 one-second pulses. Frost the cupcakes as desired. The frosted cupcakes can be kept in an airtight container at room temperature for up to 3 days.