Preheat oven to 350˚F. Prepare baking sheets by lining with parchment.
In a large bowl, cream the butter, sugar, and brown sugar with an electric mixer on high. Lower the speed to medium, then add the egg and vanilla extract.
In a separate bowl, sift together the flour, cocoa powder, baking soda, baking powder, and salt. With the mixer on low speed, add the flour mixture to the butter/sugar mixture, and beat until incorprated. Fold in the choclate chips.
Form into 1 1/2-inch balls, and arrange 2 inches apart on the prepared baking sheets. Bake 10-12 mintues, just until the centers are set. Allow to cool 5 minutes on the baking sheets, then transfer to wire racks.