Preheat oven to 350 degrees F.

In a large bowl, combine the butter and sugar, beating until fluffy.

Add eggs one at a time.

Gradually add the cocoa powder and flour, blending thoroughly.

Cover and chill for at least one hour.

Shape into balls about the size of a tablespoon.

Roll each ball in the powdered sugar and place on parchment paper.

Bake for 12 minutes

Allow cookies to cool for 5 minutes before removing and place on a rack to finish cooling.

Sprinkle with more powdered sugar if you wish!