Cream shortening in a medium mixing bowl; gradually add sugar, beating well. Add eggs, one at a time, beating well after each addition.
Combine flour, baking powder, and soda. Add flour mixture to creamed mixture alternately with buttermilk, beginning and ending with flour mixture. Stir in vanilla.
Pour batter into 2 greased and floured 8-inch round cake pans. Bake at 350° for 35 minutes or until a wooden pick inserted in center comes out clean. Cool in pans 10 minutes; remove layers from pans, and cool completely.
Spread Pineapple Frosting between layers and on top of cake.