Preheat the oven to 350ºF. Line a baking sheet with parchment paper or a silpat.
In a large bowl sift or whisk together flour, cocoa, baking soda, and salt.
In the bowl of a stand mixer fitted with the paddle attachment, cream butter and sugar until light and fluffy. Add eggs and vanilla and beat well. Add the flour mixture in about three parts, mixing just until incorporated after each addition. Remove the bowl from the stand mixer and use a wooden spoon or rubber scraper to fold in the chocolate chips.
Drop teaspoonfuls of dough onto the prepared baking sheet. Bake 8-9 minutes. Do not overbake, cookies will still be soft. Cool slightly on the cookie sheet before removing to a wire rack to cool completely.