Cream shortening; gradually add sugar, beating well. Add egg yolks; beat well.
Combine flour and baking powder; add to creamed mixture alternately with milk, beginning and ending with flour mixture.
Beat egg whites (at room temperature) until soft peaks form; gently fold into batter.
Pour batter into a lightly greased and floured 13- x 9- x 2- inch baking pan. Bake at 350° for 30 minutes or until a wooden pick inserted in center comes out clean. Cool in pan 10 minutes. Spread Quick Fudge Frosting on top of warm cake. Cut cake into squares to serve.