Begin by preheating your oven to 350°F (175°C). Coat a 9x13 baking dish with oil and flour or non-stick baking spray. In a large mixing bowl, combine 1 box yellow cake mix, 4 large eggs, 1 cup oil, and 11 oz mandarin orange slices. Beat until the batter becomes smooth.
Pour the batter into your prepared baking dish. Bake the cake on the center rack for 30-35 minutes, or until you can insert a toothpick into the center and it comes out clean. Allow the cake to cool completely before adding frosting.
Add all frosting ingredients (room temperature 8 oz Cool Whip, 20 oz crushed pineapple, and 3.5 oz Jell-O instant vanilla pudding mix) to a medium mixing bowl and mix until thoroughly combined.
Pour the frosting mixture over the cooled cake and place it covered in the fridge to chill and set before serving.
