Preheat oven to 375 degrees.
Place unsweetened chocolate in a heavy, small saucepan.
Cook and stir over low heat until chocolate is melted.
Set aside to cool.
In a large bowl beat butter with an electric mixer on medium to high speed for 30 seconds.
Add granulated sugar, brown sugar, baking soda, and cooled chocolate.
Beat until combined, scraping sides of bowl. Beat in eggs and vanilla until combined.
Gradually beat in flour.
Stir in the white baking bar, semisweet chocolate, and nuts.
Drop by rounded tablespoons 3 inches apart onto ungreased cookie sheet.
Bake 9 to 11 minutes or until edges are firm.
Cool on cookie sheet 1 minute.
Transfer to a wire rack to cool completely.