Finely grind nuts, flour and salt in processor.
Using electric mixer, beat 1/2 cup powdered sugar, butter and vanilla and almond extracts in large bowl until light.
Add nut mixture and beat just until blended.
Cover and chill until firm, about 1 hour.
Preheat oven to 350°F. Lightly butter 2 heavy large baking sheets.
For each cookie, roll 1 rounded tablespoonful dough into cylinder; pinch ends to taper. Place in crescent shape on baking sheet.
Bake until bottoms of cookies are just golden, about 15 minutes.
Transfer baking sheets to racks. Cool cookies.
Sift 1/4 cup powdered sugar over.
Makes about 18 cookies.
Note: Can be made 3 days ahead. Store in an airtight container at room temperature.