Preheat oven to 350º F. Line a cookie sheet with parchment paper.
Using the paddle attachment cream butter and sugars together in a stand mixer. Beat for a few minutes until light and fluffy. Scrape down the sides when needed.
Add egg and vanilla and mix well.
In another medium bowl whisk together flours, salt, soda and cocoa powder.
With the mixer on low, slowly add the flour mixture to the mixer and gently mix until combined. Remember to scrape down the sides with a spatula.
Add chocolate chunks and stir.
Using a medium ice cream or cookie dough scooper drop cookies onto parchment paper. Cook for about 10-12 minutes. Take them out when they are still soft in the middle because they will set. Let them hang out on cookie sheet for five minutes then carefully transfer them to a rack to cool.