In a small saucepan, melt the butter. Add vanilla extract to it. Leave to cool for 10 minutes.
Meanwhile, either in a large bowl combines the next 6 ingredients (flour through to salt). Pour in the butter and mix until it looks like moist clumpy sand with no floury patches. Add the egg and mix in for a few seconds, then the chopped chocolate and mix until well distributed - but not for too long!
cup cookie scoop, scoop up some of the dough and smoosh it into the scoop until it's just full. Turn out onto a lined cookie tray, spacing each mound 3" apart. Repeat with all of the cookie dough. Cover with cling film and refrigerate for anywhere between 2-3 hours (the longer you wait, the better the texture and flavor).
When ready to bake preheat your oven to 200 degrees C. When ready, sprinkle the cold cookie dough with pink saltand put into the oven immediately. Bake for 8-11 minutes, until browned, with set edges, and a puffy, soft center. Let cool on the baking tray for a minute before transferring to a wire rack.