Preheat oven to 325 F. In large mixer bowl cream together butter, shortening( *Crisco is best) and sugar until light and creamy. Add eggs one at a time mixing after each egg. Mix flour and baking powder together. Add flour mixture alternately with milk to batter, mix well after each addition, begin and end with dry ingredients. Fold in chopped walnuts. Spoon batter into well greased and floured 10 inch tube pan. Bake in preheated oven for 1 hour 20 minutes or until cake tests done. Remove from oven, cool in pan 10 minutes then turn out onto serving plate, let cool completely before frosting. For Frosting Mix softened cream cheese and butter, add vanilla extract or Black Walnut flavoring to taste. Stir in powdered sugar, adjust with a little milk or powdered sugar to reach spreading consistencey if needed. Enjoy!