In the bowl of your stand mixer fitted with the paddle attachment combine the butter and sugar on medium speed for 2 minutes.
Turn mixer to low and add in the salt and cocoa powder. Mix for 15 seconds and then turn mixer up to medium and mix for 30 more seconds until the cocoa powder is evenly combined.
Turn mixer back down to low and add in the flour and chocolate chips, mixing just until dough comes together and the flour is no longer visible.
Place an 18- inch piece of plastic wrap on your counter. Place the dough onto the plastic wrap and using your hands form the dough into a 12-inch log. Wrap the dough tightly in the plastic wrap and refrigerate for at least 2 hours, or overnight.
Preheat the oven to 325°F. Line a baking sheet with parchment paper and set aside.
Unwrap the dough and slice it into approximately 1/2- inch pieces. Lay the cookies flat on the baking sheet and bake for 16-18 minutes, until set.
Transfer cookies to a wire rack to cool completely.