1Melt butter in a pan on medium heat, whisking until bubbles form and butter browns. Transfer to a bowl to cool.
2Add sugars to the browned butter and whisk.
3Add egg and vanilla, and whisk.
4Add sifted dry ingredients (flour, salt, coffee, cornflour, baking soda, and baking powder) and fold gently until some flour remains.
5Add chocolate chunks and fold until no flour streaks remain; do not overmix.
6Scoop out 75-80g cookie dough balls and chill for 1 hour.
7Place chilled dough balls 2 inches apart on a lined baking tray and bake in a preheated oven at 180°C for 11-15 minutes, or until the sides are firm and the center is soft.
8Use a round bowl to reshape cookies into perfect circles after baking. Let them set on the tray for at least 15 minutes before enjoying warm.