Preheat the oven to 350 degrees F and line a muffin tin with 4 cupcake liners.
In a medium bowl, whisk together the flour, black cocoa powder, granulated sugar, baking powder, and salt.
Add the buttermilk, vegetable oil, egg, and vanilla extract to the dry ingredients. Stir until the batter is smooth and no streaks remain.
Divide the batter evenly among the 4 liners, filling each about two-thirds full.
Bake for 18 to 20 minutes, or until a toothpick inserted in the center comes out clean. Let the cupcakes cool completely in the tin.
While the cupcakes cool, melt the chocolate chips in a microwave-safe bowl in 20-second bursts, stirring between each until smooth. Spoon the melted chocolate onto parchment paper in small wing shapes and let them set at room temperature.
In a small bowl, beat the powdered sugar, softened butter, and remaining 1 tablespoon black cocoa powder until creamy.
Spread the frosting over the cooled cupcakes and gently press two chocolate wings into the top of each one.