This is the most refreshing and delicious summertime desert ever. I have shared it with many people ever since I first had it. My original copy called for the cake to be baked in three 9-inch pans, greased and floured, at 350°F for 25 minutes. I also divide the Mandarin oranges into 2 equal parts but keep one-half of them whole. I gently stir the whole oranges into the the cake mix after it has been beaten for 2 minutes. It's more delicious when all the oranges aren't beaten into tiny pieces. I also use two 8-ounce containers of Cool Whip for the frosting. One other option is to divide the pineapple so that you add three-quarters to one cup into the cake batter.