Step 1

Preheat oven to 350 degrees Fahrenheit. Spray three 9 by 13 inch baking pans.

Step 2

Mix together cake mix, butter, eggs, juice from oranges, and vanilla in a stand mixer or with an electric mixer for 3 minutes on medium speed, scraping the sides as needed.

Step 3

Fold in oranges.

Step 4

Pour batter equally in the three prepared pans.

Step 5

Bake 15-20 minutes or until golden brown and toothpick inserted in the middle comes out clean.

Step 6

Cool cakes completely on a wire rack, then transfer to refrigerator until ready to frost.

Step 7

Once cakes are cold, stir together whipped cream, crushed pineapple, and pudding mix until blended.

Step 8

Spread one third of the frosting on first layer of cake. Top with the second layer and repeat an additional layer of frosting. Add last layer of cake and top with the remaining frosting.

Step 9

Refrigerate at least 3 hours before serving. Garnish with additional slices of mandarin oranges if desired.