Heat oven to 350°.
Grease and flour baking pan, 13x9x2 inches, or two 9 inch or three 8 inch round layer pans.
Mix butter, sugar, eggs and vanilla in large mixer bowl until fluffy.
Beat on high speed, scraping bowl occasionally, 5 minutes.
On low speed, mix in flour, baking powder and salt alternately with milk.
Pour into pan(s).
Bake until wooden pick inserted in center comes out clean, oblong 45 to 50 minutes, layers 30 to 35 minutes.
Cool.
Frost cake with Buttery Frosting.
(Can be served immediately.) Place wooden picks at intervals around top of cake to prevent wrapper from sticking to frosting.
Wrap, label and freeze.
2 hours before serving, remove Buttery Freezer Cake from freezer.
Thaw in wrapper at room temperature 1 hour.
Remove wrapper; thaw cake uncovered 1 hour.
(Or, after the first hour of thawing, cut cake into serving pieces.
Place on serving plate and thaw 30 minutes.)