Heat the oven to 150°C/130°C fan-forced.

Chop each macadamia in half. Place on a shallow baking tray and toast in the oven for around 30-40 minutes until the colour of pale honey. Cool the nuts quickly in the fridge.

Place the cold butter, sugars and vanilla in a stand mixer fitted with the paddle attachment. Beat on speed 2 for about 5 minutes, until the mix looks like sugary mash.

Sift the flour, baking powder, bicarb and 1 tsp fine salt into a small bowl and set aside. Weigh the white chocolate chips with the cooled chopped nuts and set aside.

Keeping on speed 2, add the egg to the butter mix in one go and beat for 5 minutes.

Reduce to speed 1, then add the dry ingredients and mix just until no flour is visible. Tip the chocolate and nuts in and mix until only just incorporated.

Lightly grease a baking tray with cooking oil spray. Weigh nine balls of dough to 165g each.

Roll each ball gently but don’t compact the dough. Place closely together on the tray. Chill for a minimum of 12 hours, or bake straight away.

When ready to bake, preheat the oven to 180°C/160°C fan-forced. Arrange the dough balls on the tray, spacing them apart, then sprinkle the tops with salt flakes.

Bake for 25-30 minutes until the cookies have settled with a mild dome and a crisp butterscotch-coloured upper crust.

Cool the baked cookies on the tray for 10-15 minutes.