2¼ cups cake flour, sifted
2 tablespoons unseetened Dutch-process cocoa powder
½ cup unsalted butter, room temperature
1½ cups packed light-brown sugar
2 large eggs, room temperature
1 teaspoon pure vanilla extract
1½ teaspoons baking soda
¼ teaspoon salt
½ cup sour cream, room temperature
¾ cup freshly brewed espresso
1 tablespoon instant espresso powder
Seven-Minute Frosting (see recipe below)
Coffee beans, for garnish
Preheat oven to 325ºF. Line standard muffin tins with paper liners.
Whisk together cake flour and cocoa. With an electric mixer on medium-high speed, cream butter until smooth and light. Add the brown sugar and eggs; beat until fluffy, scraping down sides of bowl as needed. Add the vanilla, baking soda, and salt; beat to combine thoroughly.
Reduce speed to low. Add flour mixture in three batches, althernating with two additions of sour cream, and beating until just combined after each. Mix together brewed espresso and espresso powder; add to batter, and beat until smooth.
Divide batter evenly among lined cups, filling each three-quarters full. Bake, rotating tins halfway through, until a cake tester inserted in centers comes out with only a few moist crumbs attached, about 22 minutes. Transfer tins to wire racks to cool completely before removing cupcakes. Cupcakes can be stored up to 3 days at room temperature, or frozen up to 2 months in airtight containers.
To finish, use a small spoon to dollop cupcakes generously with frosting and make decorative peaks. Garnish each cupcake with a coffee bean before serving.
Seven-Minute Coffee Frosting
1¼ cups sugar plus 2 tablespoons sugar
1tablespoon espresso powder
⅓ cup water
1 tablespoon corn syrup
2 large egg whites, room temperature
pinch of salt
Combine 1½ cups sugar with the water and corn syrup in a small saucepan; clip a candy thermometer to side of pan. Bring to a boil over medium heat, stirring occasionally, until sugar dissolves. Continue boiling, without stirring, until syrup reaches 230ºF.
Meanwhile, in a bowl of a standing electric mixer fitted with the whisk attachmnt, whisk egg whites on medium-high speed until soft peaks form. With mixer running, add remaining 2 tablespoons sugar, beating to combine.
soon as sugar syrup reaches 230ºF, remove from heat. With mixer on
medium-low speed, pour syrup down side of bowl in a slow, steady stream.
Raise speed to medium-high; whisk until mixure is completely cool (test
by touching the bottom of the bowl) and stiff (but not dry) peaks form,
about 7 minutes. Use immediately.