In a large bowl of an electric mixer, beat together butter and sugar until well blended.
Add eggs and vanilla and beat well...scrape down bowl and beater to make sure all is mixed before next addition
With mixer on lowest speed, alternately add flour mixture and milk. Scrape down again and beat until thoroughly incorporated.
Divide mixture into pans and bake for 30-40 minutes (will take less time if using white all-purpose flour in place of whole wheat) until a toothpick comes out of center clean. Cool on a wire rack in pan for 10 minutes, then invert onto wire rack to cool completely.
Cream butter. Add vanilla and mix well.
With mixer on medium speed, slowly add 4 cups confectioners' sugar.
After all has been incorporated, add 2 TBS. milk. check for desired consistency and add a bit more milk as needed.