How to Make It
Preheat oven to 350ºF. Toast nuts on a baking sheet until fragrant, 8 to 10 minutes, shaking sheet once halfway through. Transfer to a bowl to cool, then chop finely.
Using an electric mixer on medium-high speed, beat butter and sugar until light, about 3 minutes. Mix in flour and salt on lowest speed until just combined. Stir in nuts. Divide dough into 2 portions; shape into 5-inch squares. Wrap in plastic; chill for at least 2 hours.
Preheat oven to 350ºF. Line 2 baking sheets with parchment. Let dough rest at room temperature until pliable enough to roll. On a lightly floured surface, roll out a square of dough to 1/4-inch thickness. Use a 3-inch cookie cutter to cut as many cookies as you can. Transfer to baking sheets, leaving about 1/2 inch between each cookie. Set aside scraps. Repeat with remaining dough. Combine scraps, re-roll and cut. If dough becomes too soft to roll, refrigerate briefly.
Bake cookies until dry on top but not brown, 10 to 12 minutes. Let stand for 5 minutes on baking sheets on wire racks, then transfer cookies to racks to cool completely.