Preheat oven to 180°C (160°C fan). Line trays with baking paper.
Into one large bowl add all the ingredients below… Softened butter, Caster sugar, Brown sugar, Egg, Milk, Espresso, Vanilla, Flour, Bicarbonate of soda, Chocolate
Mix until just combined. Do not overwork the dough.
Weigh into 100g balls. Roll in the cocoa-sugar mix.
Place well spaced on trays and bake 14 minutes until edges are golden but centres are still soft.
Bang onto a surface and sprinkle with Maldon sea salt as soon as they come out of the oven.
Cool on the tray for 10 minutes before transferring to a rack.
