Mix ingredients in order given. Pour into greased jelly roll pan. Bake @ 350 for 20-30 minutes or until toothpick inserted in center comes out clean. Cool before frosting.
Soften cream cheese and margarine. Blend with hand mixer and add vanilla. Begin adding powdered sugar, add gradually until frosting is to spreading consistancy. you may need to add more than 2c. Spread over cooled bars.