In the bowl of an electric mixer, beat the butter until light and fluffy. Add the sugar and continue beating until smooth. Add the eggs one at a time incorporating completely after each addition. Add the vanilla and blend well.

In a large bowl, whisk together the flour, cocoa powder, baking powder and salt. Add the dry ingredients to the mixer bowl at low speed gradually until combined.

Chill the dough for 2 hours or until firm.

Preheat the oven to 350 degrees and line a baking sheet with parchment paper.

Pour the confectioner's sugar in a small bowl.

Using a tablespoon, scoop a rounded spoonful of dough and form into a ball using your hands. Roll the ball in the confectioner's sugar until completely covered and place on the prepared baking sheet about 2 inches apart.

Bake in a 350 degree oven for 10-12 minutes. Cool for 2 minutes on the baking sheet and then move to a wire rack to cool completely.

Store in an airtight container.