Preheat oven to 400°F.

Mix butter, sugar and vanilla extract in an electric mixer.

Gradually mix in flour and salt.

Fold in nuts or chocolate chips, if using.

Shape dough into balls and place 1 inch apart on ungressed cookie sheet.

Bake for 10 minutes, or until set but not brown.

Cool slightly, then roll in powdered sugar while still warm. Cool completely, then roll in powdered sugar again.