Heat oven to 350 deg F. In small microwave-safe bowl, place chocolate. Microwave at high (100%) 1 1/2 to 2 minutes or until chocolate is melted when stirred; cool slightly. In large mixer bowl, beat butter and sugar until well blended. Add egg and vanilla; beat well. Blend in melted chocolate, flour and baking powder. Stir in nuts, if desired. Drop by rounded teaspoonfuls onto ungreased cookie sheet. Bake 8 to 10 minutes or until almost set. Cool slightly. Remove from cookie sheet to wire rack. Cool completely. About 2 dozen cookies.
(From Hershey's chocolate package)