First, make your cookie dough! In a large bowl, using an electric mixer, cream together the butter, brown sugar, and white sugar until lighter and fluffy (3-5 minutes – don't skimp on this step!). Add in the egg plus egg yolk and vanilla extract and beat until smooth, another 30 seconds. Add in the flour, starch, baking soda, and salt and mix by hand with a wooden spoon or spatula until fully combined (it will be fairly stiff). Finally, add in the chopped white chocolate and chopped (halved) roasted salted macadamia nuts and stir to combine. Scoop dough into a smaller bowl, cover with plastic wrap, and chill in the fridge for 1 hour.