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1
Preheat oven to 325F.
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2
Line standard muffin tins with paper liners.
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3
Whisk together cake flour and cocoa.
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4
With an electric mixer on medium-high speed, cream butter until smooth and light.
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5
Add the brown sugar and eggs; beat until fluffy, scraping down sides of bowl as needed.
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6
Add the vanilla, baking soda, and salt; beat to combine thoroughly.
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7
Reduce speed to low.
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8
Add flour mixture in three batches, alternating with two additions of sour cream, and beating until just combined after each.
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9
Mix together brewed espresso and espresso powder; add to batter, and beat until smooth.
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10
Divide batter evenly among lined cups, filling each three-quarters full.
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11
Bake, rotating tins halfway through, until a cake tester inserted in centers comes out with only a few moist crumbs attached, about 22 minutes.
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12
Transfer tins to wire racks to cool completely before removing cupcakes.
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13
Cupcakes can be stored up to 3 days at room temperature, or frozen up to 2 months, in airtight containers.
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14
To finish, use a small spoon to dollop cupcakes generously with frosting and make decorative peaks.
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15
Garnish each cupcake with a coffee bean before serving.
