In a large bowl, cream together butter, sugar, orange zest, and vanilla with an electric mixer until light and fluffy. Mix in eggs and egg white one at a time, beating well after each addition. Sift together the flour, baking powder, and salt; gradually blend into the creamed mixture using a wooden spoon. Stir in the white chocolate, dried cranberries, and pistachios. Cover, and chill for 30 minutes, or until dough is no longer sticky.