Sift together baking soda, salt, baking powder, and flour. Set aside.
In a large mixing bowl, cream together butter and sugar. Beat for about 3 minutes. Add eggs and vanilla. Beat for another 3 minutes.
Add flour alternately with sour cream in three additions. Beginning and ending with flour. Cover dough with plastic wrap and refrigerate overnight or 8 hours.
In a large mixing bowl, cream butter, cream cheese. Add vanilla and powdered sugar until well blended.