Whisk the flour, cornflour, bicarb soda and salt together in a large bowl.

In another bowl, whisk the melted butter, brown sugar, caster sugar, egg, egg yolk, and vanilla extract together until combined. Add it to the dry ingredients and mix well.

Add the chocolate chips and macadamia nuts and form dough into a ball. Cover and refrigerate for about up to an hour or until firm.

Preheat oven to 180°C (fan forced) and line two baking trays with baking paper

Roll cookie dough into 1 tablespoon size balls and arrange 7cm apart on the trays. Bake for 12-13 minutes or until lightly browned on the sides. The centres will look soft.

Allow cookies to cool and harden for 5 minutes before transferring to a wire rack.