I'll be making this request soon on my son's 20th birthday. Given to me by my husband's aunt - it is yummy and gets better as it sits in frig.
You can use the sugar free cool whip and pudding.
MANDARIN ORANGE CAKE
Preheat oven to 325°; grease and flour 3 round cake pans.
11 oz. mandarin oranges (undrained)
4 eggs
½ cup oil
1 Duncan Hines butter recipe cake
Mix ingredients and beat well for 2 minutes. Pour into cake pans. Cook 30 to 35 minutes. Allow to cool before frosting.
ICING:
12 oz. cool whip
1 small pkg. instant vanilla pudding
1 15 oz. can crushed pineapple (drained well)
Mix cool whip, instant pudding and pineapple with spoon.
Frost cake between each layer and around the edges.
Refrigerate.