Preheat oven to 350. Cake-Combine the brown & white sugar in you large bowl of your kitchen aid mixer. Then add the 2 sticks of soft butter and shortening and beat until is is creamy.
Add the eggs one at a time, beating well after each addition. In another large bowl, sift together the baking powder and flour 3 times. Add the flour mixture alternately with the milk, beginning and ending with the flour and add the vanilla and combine.
For this cake you can use a 13 or 15 inch baking dish sprayed with pam. In the oven melt the 1/2 stick of butter in the dish. Now add your pineapple and brown sugar and pour your cake batter over pineapple mixture. Bake for 1 hour 10 minutes, more or less time depending on how your oven cooks. Test cake in the middle with a wooden skewer or toothpick. Remove from oven and let cool 10 or so minutes then loosen sides of cake with knife place cookie sheet over top of cake & flip it carefully. Let cool or warm before slicing depending how you like your cake.