Preheat oven to 170 degrees celsius (fan-forced).
Line two large baking trays with greaseproof paper and set aside.
In a large bowl, beat the softened butter, caster sugar and brown sugar until pale and creamy.
Add the egg and vanilla extract and continue to beat until well combined.
Add the salt.
Sift the bi-carb soda and plain flour over the top of the mixture and fold through.
Add the white chocolate chips and the chopped macadamia nuts and stir through.
Place the dough into the fridge for 15 minutes (optional).
Roll into heaped teaspoon sized balls and place onto the prepared trays (leave a gap between each cookie to allow for spreading).
Cook for 8-10 minutes or until just lightly golden.
Allow to cool slightly on the baking trays before transferring to a wire rack to cool completely.