Preheat oven to 325°F Grease and flour a 10-inch tube or Bundt pan and set aside.

Cream together the butter and shortening with an electric mixer on medium speed for 2 minutes. Gradually add the sugar.

Add the eggs, one at a time, beating well between each addition.

In a separate bowl, sift together the flour and baking powder.

Gradually add to the butter mixture, alternating each addition with the milk.

Mix until just blended.

Stir in the vanilla and walnuts.

Pour into the pan and bake for 90 minutes, or until a toothpick comes out clean.

Remove from the oven and allow to cool for 10-15 minutes. Remove from the pan and cool thoroughly on a wire rack.

Dust with powdered sugar before serving.