Toast the macadamia nuts in a skillet over medium heat for 3 - 5 minutes until toasty and fragrant. Set aside to cool for 15 - 30 minutes.
Transfer cooled macadamia nuts to a food processor and pulverize into small pieces no larger than ¼”. You can also chop the nuts on a cutting board with a knife if you don’t have a food processor. Set aside.
Beat together softened butter, sugar, and vanilla extract in a mixing bowl until combined and fluffy.
Sift flour and malted milk powder into a small mixing bowl. Stir in salt, chocolate chips and the chopped macadamia nuts. Add the flour mixture to the butter mixture. Mix until a dough forms.
Scrape the dough out of the bowl onto a piece of plastic wrap, roll into a log about 12” long or divide in half and roll into 2 logs about 6” each. Refrigerate for at least 30 minutes to 1 hour. If the dough is too soft at this point, you may want to refrigerate for 30 minutes, reshape the logs to make sure they are round, and freeze for another 30 minutes to speed up the process.
When the dough is ready, take it out of the refrigerator or freezer and cut it into ½” slices. Place the cookies in a container and freeze for about 15 minutes while the oven is preheating.
Preheat the oven to 350°F.
When the oven is ready, place cookies on a parchment lined baking sheet 1” - 2” apart. Sprinkle granulated sugar over the top of cookies generously and bake for 15 minutes.
Remove from the oven, let cookies cool on the baking sheet for 5 - 10 minutes before transferring to a wire rack to cool completely
Optional: dip cooled cookies in melted chocolate to add another layer of chocolate flavor.