Use weight measurements for the nut flours: I prefer weighing almond and pistachio flour for these cookies because how tightly nut flour settles into a measuring cup can make a noticeable difference in the dough.
Watch homemade pistachio flour carefully: Pulse the pistachios rather than running the food processor continuously. Stop once they're finely ground so they don't start releasing too much oil.
Whip to soft peaks: The egg whites should hold a soft peak that curls over rather than standing stiffly upright.
Expect sticky dough: This isn't meant to feel like regular cookie dough. Powdered sugar on your hands makes it much easier to roll.
Be generous with the powdered sugar: A good coating gives you a much more noticeable crackled finish once the cookies spread.
Check at 20 minutes: You're looking for cracked tops and lightly golden bottoms rather than deeply browned cookies.
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