Pistachio Shortbread Cookies
- Mix flour, powdered sugar, and saslt in processor. Add butter, pistachios, egg yolk, and vanilla.
- Using on and off turns, mix until moist ball forms. Transfer dough to work surface. Divide dough in half. Form each half into 8 X 1 1/4" log (if dough is too soft, chill until firm, about 30 minutes). Wrap logs in plastic, refrigerate until firm, about 4 hours. Can be made 5 days ahead, keep chilled.
- Preheat oven to 325 degrees.
- Slice logs into 1/4" rounds, rolling log every few slices to retain round shape. Place rounds on ungreased baking sheets, spacing 1" apart.
- Bake shortbreads until barely golden, about 18 minutes. Cool shortbread on baking sheets.
- Store in airthight container at room temperature.