Preheat oven to 170°C (350°F). Line 12 muffin cups with paper liners.
In a large bowl, whisk together the flour, cocoa powder, baking powder, baking soda, and salt. Set aside.
In a measuring cup, combine the buttermilk and milk (or coffee). Set aside.
In the bowl of a stand mixer, cream the butter, then add the sugar and beat until the mixture is pale and fluffy, about 2 minutes. Mix in the egg and vanilla extract. At low speed, incorporate the dry ingredient and buttermilk-coffee mixture, alternating between the two. Mix until just incorporated (do not overbeat). Using a spatula, fold in the dark chocolate chips.
Spoon some batter into each cavity of the prepared muffin pan until they are two-thirds full. Bake for about 20 minutes, or until a toothpick inserted into the center of a cupcake comes out clean.
Let the cupcakes cool completely on a wire rack.
For the ganache
Place the chopped chocolate, butter, and cream in a large microwave-safe measuring cup. Heat up the chocolate mixture by 30 second bursts at the low temperature setting, mixing often until the chocolate is completely melted. Whisk in the black food coloring. Let the ganache cool to room temperature.
Transfer to a pastry bag fitted with a round or star tip, or store in an airtight container, and refrigerate until ready to decorate the cupcakes.
Take the ganache out of the refrigerator 30 to 60 minutes before icing the cupcakes. If the ganache still seems stiff, « loosen it up » simply by holding the pastry bag in warm hands, or whisk the ganache again to make it easier to spread. Generously ice the cupcakes with ganache. Decorate with sugar pearls or other edible garnishes.