1. Sift together flour, baking powder, salt and sugar.
2. In a mixing bowl, cream shortening, egg, milk and vanilla together. Gradually add to sifted mixture and beat 3 minutes at low to medium speed until smooth.
3. Combine brown sugar and melted butter and pack into a greased 9 inch round cake pan. Arrange crushed pineapple on top of brown sugar.
4. Pour batter over fruit and brown sugar and bake at 350 degrees F for 35 to 40 minutes.