Adapted from allrecipes.com
(18.25 ounce) package yellow cake mix
cup vegetable oil
(11 ounce) can mandarin orange segments
(8 ounce) container frozen whipped topping, thawed
(20 ounce) can crushed pineapple with juice
(3.5 ounce) package instant vanilla pudding mix
Preheat oven to 350 degrees F (175 degrees C). Grease and flour a 9x13 inch pan. In a large bowl, combine cake mix, eggs, oil and mandarin oranges with juice. Beat until smooth. Pour batter into prepared pan. Bake in the preheated oven for 35 to 40 minutes, or until a toothpick inserted into the center of the cake comes out clean. Allow to cool. To make the topping: In a large bowl, beat together whipped topping, pineapple with juice and dry pudding mix until blended. Spread on cake.