Take the name of this recipe at face value: You can truly use most any type of nut here, depending on your preference: hazelnuts, walnuts, almonds, pecans, cashews, etc. They will all work equally well to create delicious cookies, each with its own unique flavor (or here's a thought: use a mixture for a more nuanced result). Don't be tempted to rush the process; the dough will be much easier to work with after being allowed to rest for an hour.