HoHo Bars Recipe

Prepare cake mix according to directions. Pour batter into greased and floured jelly roll pan. Bake 12 - 15 minutes at 350°. Cool. Combine sugar, butter, shortening, milk, vanilla and salt. Beat until fluffy, about 15 minutes. Spread over cooled cake. Heat frosting in microwave for 20 seconds to soften. Spread frosting over white cream layer. Note: Cream mixture looks curdled as if it won't be creamy, just keep beating it. Eventually it gets light and fluffy.