Cream shortening; gradually add sugar, beating well.
Combine flour, baking powder, and salt; add to creamed mixture alternately with milk, beginning and ending with flour mixture. Stir in vanilla.
Beat egg whites (at room temperature) until stiff peaks form; fold into batter.
Pour batter into 2 greased and floured 8-inch round or square cake pans. Bake at 350° for 25 minutes or until a wooden pick inserted in center comes out clean. Cool in pans 10 minutes; remove layers from pans, and let cool completely.