Preheat the oven to 350°F. Grease or line a mini muffin tin. Brew a strong cup of coffee and let it cool completely.
In a small bowl, combine the flour, cocoa powder, baking soda, baking powder, and salt.
In another bowl, pour together 1/2 cup milk and all but a few tablespoons of the cooled coffee (should equal about 3/4 cup of liquid).
Using a stand mixer on medium speed, beat the butter and sugar until creamy. Add the eggs one at a time, stirring until blended.
Alternating between 1/4 cup of the flour mixture and a few tablespoons of the coffee mixture, add them slowly to the butter and sugar mixture until fully incorporated. The batter should be smooth and not too thick.
Add in the chocolate chips, vanilla extract, and coffee extract (if using).
Use a half tablespoon measuring spoon to scoop the batter into the prepared cupcake tin.
Place the tin in the preheated oven and bake for 18-20 minutes or until the tops of the cupcakes have puffed up and are springy to the touch.
Remove the cupcakes from the oven and allow them to cool in the tin for a few minutes before transferring them to a cooling rack to cool completely.
While the cupcakes are cooling, use a hand mixer to combine 2 tablespoons of butter with the powdered sugar, adding 1/4 cup of sugar at a time.
Slowly incorporate the cooled black coffee and coffee creamer in 1 tablespoon increments.
Continue to add powdered sugar until the icing has reached a thick consistency, slightly thicker than average toothpaste. If the mixture is too dry, add more coffee or milk. If it's too runny, add more powdered sugar.
Use an icing bag or a ziplock bag with the corner cut off to swirl the icing onto the cooled cupcakes. Serve right away and enjoy!