Grease and flour a tube pan or Bundt pan. Set aside.
With an electric mixer, cream butter and sugar until smooth, about 4 to 5 minutes.
Add eggs, one at a time, beating well after each addition.
Whisk together flour, baking soda and salt. Set aside.
Stir vanilla extract into sour cream. Set aside.
Add flour mixture, gradually, to wet ingredients alternating with sour cream mixture. Mix only until all traces of dry ingredients are gone.
Toss remaining 1/3 cup flour into chopped apples.
Stir apples and flour into batter, gently.
Pour into a prepared tube pan or Bundt pan. I used a 14 1/2 cup Bundt pan and the batter filled it slam full. Don't use a smaller one.
Bake at 325 minutes for 1 hour 20 minutes or until toothpick inserted comes out clean.
Place pan on cooling rack for about 20 minutes.
Loosen sides of cake from pan and invert onto a plate. Let cool completely before slicing.
Dust with powdered sugar before serving.