Toast the macadamia nuts by putting them into a clean, dry frying pan and frying them on medium/high heat until they start to become fragrant or are lightly browned. Stir frequently to prevent burning. Cool completely.

Combine softened butter and sugars in a large mixing bowl; cream until smooth. Beat in egg, and stir in vanilla, white chocolate, and toasted nuts.

Combine the dry ingredients in a sieve or sifter and sift into the creamy butter mixture; stir to combine, kneading if necessary to mix thoroughly. You can cover the chill the dough at this point, or use it immediately.