Sift together the flour, baking powder and salt; set aside. In another bowl, cream the sugar and shortening; add eggs. Add milk alternately with the dry ingredients to creamed mixture. Add vanilla and mix well. Grease a 10 inch round cake pan and line with brown sugar, about 1/2 inch deep. Dot with butter. In the pan, place slices of pineapple with a amaraschino cherry in center of each. Pour the cake batter over the mixture in the pan. Bake at 350 for 50 minutes. Turn out onto plate and serve hot with whipped cream topped with cherries.