Preheat your oven to 175°C (350°F) and line a muffin tin with paper liners.
Sift together the flour, cocoa powder, and baking soda into a large mixing bowl. This ensures an even distribution of dry ingredients and a smooth batter.
In a separate bowl, beat the softened butter and granulated sugar with an electric hand mixer until the mixture is pale, fluffy, and fragrant, about 3-4 minutes. This creates a tender crumb and enhances flavor.
Add eggs one at a time to the butter mixture, beating well after each addition. The eggs should incorporate fully, making the mixture smooth and slightly glossy.
Mix in the vanilla extract, and then alternate adding the dry ingredient mixture and buttermilk to the wet ingredients. Start and end with the dry ingredients, mixing just until combined each time. The batter will be thick but smooth.
Divide the batter evenly among the paper liners, filling each about two-thirds full. Use a spoon or scoop for clean, even portions.
Bake in the preheated oven for 18-20 minutes, until a toothpick inserted into the center comes out with moist crumbs. The cupcakes will feel springy to the touch.
Remove the cupcakes from the oven and allow them to cool in the tin for 5 minutes. Then, transfer them to a wire rack to cool completely, which helps prevent sogginess and sets their moist crumb.
Once cooled, frost the cupcakes with your favorite frosting—rich cream cheese or dark chocolate ganache work beautifully—using a spatula or piping bag for a polished look.
Enjoy these striking, moist black velvet cupcakes with a glass of milk or your favorite hot beverage for a cozy treat.
