Cream butter, gradually add sugar, add vanilla. Cream butter, sugar, and vanilla thoroughly. Add the flour gradually and work in by hand. Put the mixture in a 9 X 13 glass pan. Spread and pat down. With the back of a knife, mark into wedges or squares and prick thoroughly with a fork. Bake at 300 degrees for 45 minutes or until golden brown. Cool in pan, remarking wedges or squares while still warm.