Preheat the oven to 350°F and line a cupcake pan with 4 paper liners.
In a mixing bowl, whisk together the flour, dark cocoa powder, sugar, baking powder, and baking soda.
Add the egg, milk, vegetable oil, and vanilla extract to the dry ingredients. Stir until the batter is smooth.
Fold in the semisweet chocolate chips until evenly distributed.
Divide the batter evenly among the 4 liners and bake for 18 to 20 minutes, or until a toothpick inserted in the center comes out clean.
Let the cupcakes cool completely on a wire rack.
Spread chocolate frosting over each cooled cupcake.
Press two cookie halves into the frosting on each cupcake to form bat wings.