Beat butter, sugar, egg and vanilla in medium bowl until well blended. Stir together flour, baking soda and salt; add to butter mixture, beating well.

If necessary, refrigerate dough until firm enough to handle.

Remove wrappers from chocolate pieces.

Heat oven to 350°F.

Shape dough into 1-inch balls; roll in ground nuts.

Place on ungreased cookie sheet.

Bake 10 to 12 minutes or until almost no imprint remains when touched lightly in center.

Remove from oven; immediately press a chocolate piece into center of each cookie.

Carefully remove from cookie sheet to wire rack.

Chocolate should be set before storing.