In a bowl of an electric mixer, beat together the butter and sugar on medium high speed until light and fluffy.
Beat in the eggs and vanilla.
In a separate large bowl, sift together flour, cocoa powder and baking powder.
Add the sifted dry ingredients to the butter mixture and stir until just combined.
Stir in the chocolate chips.
Cover the dough and chill for 2 hours.
Pre-heat your oven to 350°F.
Roll the dough into 1 inch balls, and then roll in icing sugar.
Place on a parchment lined baking sheet 2-3 inches apart.
Bake for 9-12 minutes.
Transfer to a wire rack to cool completely.