In a small bowl, whisk together the flour, cocoa, salt, baking powder and baking soda and set aside.  Use your electric mixer to cream together the butter and both sugars for a few minutes until very light and fluffy, scrape down the sides, add the egg and vanilla and beat again.

Turn the mixer to low and carefully add in the dry ingredient mix, then all of the chocolate and mix again until just combined.  Use a golf ball-sized cookie scoop to portion out dough balls and place them on a tray that will fit in your fridge.  Cover and chill overnight.

When you’re ready to bake, preheat the oven to 350 and line a couple of large baking sheets with parchment.  Space the chilled dough balls about 3 inches apart to allow for spreading and bake for a total of 15 to 18 minutes.  Set a second timer for 10 minutes, check the cookies, and if they haven’t really flattened at all then carefully remove the pan and give it a couple of smacks on the stove top – or on a large cutting board if you don’t have well-loved, beaten up grills like I do, then put them back in the oven.  The cookies are done when they appear to be set, but are still soft-looking in their middles.  Allow the cookies to cool completely on the pan, but if you need the pan, then carefully slide the cookies, on the parchment, to a rack to cool.  These won’t last!