Beat butter at medium speed with an electric mixer until creamy; gradually add sugar, beating well. Add eggs, 1 at a time, beating until blended after each addition.
Combine cake flour and next 3 ingredients; add to butter mixture alternately with sour cream, beginning and ending with flour mixture. Beat at low speed until blended after each addition. Stir in vanilla. Follow baking directions for Chocolate Truffle Angel Cake or Miniature Chocolate Truffle Tree Cakes.