Preheat oven to 350 degrees. Grease 15x10x2-inch cake pan.
In a large bowl, combine cake mix, oil, and eggs; beat until mixture is well-blended.
Add mandarin oranges with juice; beat 2 minutes longer.
Spoon batter into prepared cake pan.
Bake 25-30 minutes or until a pick inserted in center comes out clean. Remove and cool completely, about one hour.
When cake is cool, prepare frosting: In a small bowl, mix pudding with enough water until well-blended and smooth. In a large mixing bowl, gently fold pudding mixture into the Cool Whip.
Frost cake. Sprinkle with shaved almonds, as shown.