Preheat oven to 350 degrees. In a large bowl, combine butter and shortening. Beat with electric mixer on medium to high speed for 30 seconds. Add sugars, baking powder, baking soda, and salt; beat until combined.
Beat in eggs and vanilla. Add flour and cocoa powder; beat on low speed until combined. Stir in oats, semisweet chips, white baking chips, and nuts.
Using 1/4 cup dry measuring cup, drop dough 3 inches apart onto greased cookie sheet. Press dough into 3 inch circles. Bake for 12 to 14 minutes or just untiln edges are firm and centers are set. Cool on cookie sheet for 1 minute. Transfer cookies to wire rack; cool.