In a large saucepan, melt together the butter, oil, and cocoa powder over low heat to prevent scorching. Remove from heat. Stir in the sugar and vanilla, blending well. Add eggs one at a time, then mix in dry ingredients just until blended. Fold in nuts and choc chips. Spread batter in a greased and floured 13 x 9 pan. Bake 35-40 minutes. Recipe By : Nancy Shour