Add butter to a small saucepan and place over medium heat. Whisk frequently as it melts and keep your eye out for brown specks and a delicious nutty aroma. Once browned, remove from heat and allow to cool to room temperature.
Preheat oven to 170ºC. Line a tray with baking paper.
In a bowl add sugars and cooled brown butter. Stir together. Add egg and vanilla extract and mix.
Add flours, baking soda and salt and fold through until just combined.
Roughly chop chocolate. Add to cookie dough and mix through. Cover dough and allow to chill for at least 20 minutes.
Using an ice cream scoop, scoop balls of dough on to the prepared baking tray, careful to not overcrowd. (I used two trays). Bake for 12 minutes before transferring to a wire rack to cool.