Preheat the oven to 350. Line 3 half sheet pans with parchment paper. Put ½ cup sugar in a small bowl and set aside.
Whisk the flour, cocoa powder, baking soda, and salt together in a medium bowl.
Using a standing mixer, cream the butter and 2 cups sugar together until light and fluffy, 3-5 minutes. Add the eggs and vanilla, and beat to combine.
Add the flour mixture and mix on low until completely combined.
Shape the cookie dough into 24 balls, and roll each ball in the set-aside sugar. Place cookies on the prepared sheet pans (8 can fit on each) and bake for 11-13 minutes, until the edges have set and the centers are puffed and starting to crackle.
Remove from the oven and move the pan to a wire rack, letting the cookies cool.