In a medium bowl, whisk together the flour, cocoa powder, baking soda, and salt. Set aside until ready to use.
In a large bowl, using a hand mixer, or in the bowl of a stand mixer, beat the butter and sugars on medium speed until fully creamed (about 3-4 minutes). Beat in egg, and vanilla. Scrape down the sides with a rubber spatula and continue to mix until fully combined. Slowly add in the dry ingredients. Add chocolate chips and mix with a rubber spatula. Cover dough with plastic wrap, and chill for at least 4 hours or overnight.
Remove cookie dough from the refrigerator and allow to sit at room temperature for 15 minutes.
Preheat oven to 350º F. Line 2 cookie sheets with parchment paper.
Roll dough into one-inch balls. Gently roll in the remaining granulated sugar and then generously coat each ball in confectioners' sugar before placing onto prepared cookie sheets.
Bake for 10 minutes. Cool cookies for 2 minutes on the baking sheets, then transfer to a wire rack to cool completely. Enjoy!
