In a small pan, melt baking bar; set aside. In small bowl or on a sheet of wax paper, combine flour, baking powder and salt. Set aside.
In large mixing bowl, beat butter and sugar until creamy. Blend in egg and vanilla. Beat in melted chocolate. Gradually beat in flour mixture until soft dough forms. Shape dough into ball; flatten to 3/4 inch thickness. Wrap in plastic wrap; refrigerate 15 minutes, until firm.
Divide dough into quarters for easy handling. Heat oven to 350 degrees. On lightly floured surface, with floured rolling pin, roll dough to 1/4 inch thickness. Cut dough into desired shapes. Place on ungreased baking sheets.
Bake 8-10 minutes, until edges are lightly browned. Let stand 2 minutes. Remove and cool completely. Decorate as desired. Makes about 3 1/2 dozen cookies 2 1/2 to 3 inches in diameter.
