Preheat oven to 350 degrees F (177 degrees C) and place rack in center of oven. Line two baking sheets with parchment paper.
In the bowl of your electric mixer (or with a hand mixer), beat the butter and sugars until light and fluffy (2-3 minutes).
Add the egg and vanilla extract and beat until incorporated.
First sift together the cocoa powder, flour, baking powder, and salt and then add to the butter and egg mixture. Mix just until incorporated. Fold in the the chocolate chips.
Using a small ice cream scoop or two spoons, place about 1 1/2 tablespoons of batter on the prepared baking sheet, spacing about 2 inches (5 cm) apart.
Bake for approximately 8 – 10 minutes or until the the cookies are still soft in the center but are firm around the edges. Remove from oven and let cookies cool on baking sheet for about 5 minutes before removing the cookies to a wire rack to cool completely.