PREHEAT oven to 350° F.
COMBINE flour, cocoa, baking powder and salt in small bowl. Beat butter and peanut butter in large mixer bowl on medium speed for 30 seconds. Beat in granulated sugar and brown sugar. Beat in eggs and vanilla extract. Gradually beat in flour mixture. Stir in morsels and nuts. Drop by rounded teaspoons onto ungreased baking sheets.
BAKE for 14 to 16 minutes or until set. Let stand for 2 minutes; remove to wire racks to cool completely.