In a heavy medium saucepan heat 1 cup of the chocolate pieces, unsweetened chocolate, and butter or margarine till melted, stirring constantly. Transfer to a large mixer bowl to cool slightly. Stir together flour, baking powder, and salt.
• Add eggs, sugar, and vanilla to chocolate mixture and beat well. Add flour mixture and beat till well mixed. Stir in remaining chocolate pieces and nuts.
• Drop by heaping teaspoons onto a lightly greased cookie sheet. Bake in a 350° oven for 8 to 10 minutes or till edges are firm and surface is dull and cracked. Cool on cookie sheet for 1 minute, then remove and cool thoroughly.