Preheat oven to 350F and line a muffin pan with cupcake liners.
Whisk together flour, cocoa powder, baking powder, and salt in a bowl.
In a separate bowl, blend together egg, oil, sugar, and vanilla extract.
Blend the wet mixture into the dry ingredients.
Stir the milk in just until batter is smooth.
Fold in the chopped cookies.
Divide the batter into the muffin pan and bake for 20-25 minutes.
Take muffins out of the oven and leave to cool.
Dot mini marshmallows with black food coloring.
Blend together ingredients for the frosting. Transfer to a piping bag with a fine star tip.
Pipe icing onto cupcakes then decorate with marshmallow eyeballs and chocolate chip cookies.