Step 1

Preheat oven to 375 degrees. Place hazelnuts on a baking sheet and toast until golden and fragrant, 10 to 15 minutes. Remove from oven and let cool completely. Reduce oven temperature to 350 degrees. Pulse in a food processor until just finely ground (do not grind into a paste).

Step 2

In the bowl of an electric mixer fitted with the paddle attachment, cream butter and sugar until light and fluffy, 2 to 3 minutes. Add flour, ground hazelnuts, and salt; beat until dough forms. If needed, drizzle in 1 to 2 tablespoons water, 1 tablespoon at a time, to help form a dough. Dough can be wrapped well in plastic and refrigerated up to 1 day or frozen up to 3 months (thaw in refrigerator before using).

Step 3

Roll dough into 1-inch balls and transfer to parchment-lined baking sheets, spacing 2 inches apart. Press balls with tines of fork to flatten. Bake until edges are golden, rotating sheets halfway through, 12 to 15 minutes. Transfer sheets to a wire rack and let cookies cool completely. Cookies can be stored in an airtight container at room temperature up to 3 days.