Toast raw hazelnuts at 350 degrees Fahrenheit for 5-7 minutes until fragrant. Cool the nuts to room temperature, then husk them by rubbing a handful of hazelnuts between your hands. This should do a pretty good job of getting rid of most of the skins. Some will remain – that’s OK.
To make finely ground nuts, place toasted and husked hazelnuts and ¼ cup sugar into food processor and process until finely ground.
Add ¾ cup and 2 tablespoons of flour and a pinch of salt to the food processor and pulse to combine. Add butter and process until dough forms, scraping the sides of the food processor bowl with spatula if necessary. The dough will be soft.
On a flour-dusted surface, roll dough into 2 logs, each about 1 inch wide. Wrap each log in plastic wrap and place wrapped cookie dough in the freezer for 30 minutes, then in the refrigerator for 30 minutes.
Preheat oven to 325 Fahrenheit.
After cookie dough has been in the freezer and in the refrigerator, unwrap plastic and slice each log into thin cookie slices.
Place cookie slices on a parchment-lined ungreased baking sheet, spacing 2 inches apart.
Bake for about 12-15 minutes, don’t let the cookies get brown.
Cool cookies on baking sheet for 5 minutes, after that transfer cookies to wire rack to continue cooling. Using sifter, sprinkle cookies with powdered sugar.
Store cookies in airtight container – they can last about 2 weeks.