Preheat your oven to 350°F and line a baking sheet with parchment paper or a silicone mat.
Beat the sugar, butter, and vanilla together until just combined in a smooth paste.
Add in the cocoa powder, flour, and salt and fold or mix in by hand until a soft dough begins to form.
Dump it onto parchment, a cutting board, or silicone baking mat when there are still some crumbs loose and press it gently together like pie dough, until uniform.
Either roll it into a log, wrap in plastic wrap, and chill for 30 minutes, or roll it out into sheets 1/4"-1/2" thick and cut out shapes with cookie cutters.
If you rolled it into a log, remove and slice 1/4-1/2" thick rounds and place on baking sheet.
Bake for 7 minutes, or until the edges look set and the middle no longer looks wet.*
Notes
The number of cookies you get will largely vary based on the size of the cookie cutter or the thickness of the log you rolled it in to.*Bale 1-2 minutes longer for crisper cookies, the 7 minutes produces a soft cookie.