Preheat oven to 350° F. Spray a 13 x 9-inch cake pan (or two 8-inch round cake pans) with cooking spray and set aside.
In a large bowl, beat together cake mix, eggs, and oil on low speed for about 30 seconds. Beat at medium speed for 2 minutes. Add mandarin oranges (with their syrup) and mix on low speed for about 30 seconds, or until completely combined.
1 (15.25 oz) box yellow cake mix, 4 eggs, 1 cup vegetable oil, 1 (15 oz) can mandarin oranges in syrup, NOT drained
Bake cake for about 30 minutes, or until a toothpick inserted in the center comes out clean.
Allow cake to cool completely.
In a separate large bowl, gently fold together whipped topping, dry pudding mix, and drained crushed pineapple. Spread “frosting” on cooled cake.
1 (8 oz) container frozen whipped topping, thawed, 1 (3.4 oz) box vanilla instant pudding mix (just the dry mix…do not prepare the pudding), 1 (20 oz) can crushed pineapple, well drained
Refrigerate until ready to slice and serve!