Preheat oven to 190c
Brown the butter in the skillet. Do this by melting the butter over medium heat and keep bubbling it until it turns a golden caramel colour to reach the brown butter stage - this is when the milk solids (the little particles floating in the butter) will be brown. Remove from the heat and allow to cool slightly then add the brown sugar, granulated sugar, and salt.
Once cool to the touch, (you dont want to scramble your eggs) stir in eggs and vanilla until eggs are incorporated. Add flour and bicarbonate of soda and mix until the dough comes together. Stir in ¾ chocolate, reserving the remaining chocolate, until evenly distributed.
Scatter the remaining chocolate over the cookie and sprinkle with sea salt.
Bake cookie until outer edges are browned and slightly puffed, 20–25 minutes. Serve immediately with scoops of ice cream for a seriously delicious pudding or let cool in the skillet for 1 hour (if you can resist) and cut into slices.