Preheat oven to 350. Line baking sheet with parchment paper.
Combine the flour, cocoa powder, baking soda and salt. Set aside.
In the bowl of a stand mixer, beat the butter on medium until smooth.
Add 1 ¾ cups sugar and beat on medium until combined.
Add egg and vanilla and beat until smooth.
Add the flour mixture and beat on low until just combined.
Place the remaining 1 cup of sugar in a bowl.
Roll the dough into balls. Roll each dough ball in the sugar and place on the baking sheet.
Bake for 11 - 14 minutes or until the edges have set and the centers are puffed and starting to crack.
Transfer the baking sheet to a wire rack and let the cookies cool completely on the pan.