01 -
Preheat oven to 350°F. Spray a 9x13-inch baking dish with nonstick cooking spray.
02 -
Drain the can of mandarin oranges, setting aside 1/2 cup of the juice. Discard the rest of the juice.
03 -
Combine 1 box yellow cake mix, 1/2 cup unsalted butter, 1/2 cup mandarin orange juice, 4 large eggs, and 1 teaspoon vanilla extract. Beat for 3-4 minutes on medium-high.
04 -
Add the drained mandarin oranges and gently stir until combined, leaving some of the oranges chunky.
05 -
Spread the batter into the prepared baking dish and bake for 25-30 minutes, or until a toothpick inserted in the center comes out clean. Remove from oven and cool completely.
06 -
Drain the can of crushed pineapples very well, setting aside 3/4 cup of the juice. Discard the rest of the juice.
07 -
In a bowl, stir together 3/4 cup pineapple juice with the vanilla instant pudding mix and powdered sugar.
08 -
Fold in 4 ounces Cool Whip, and then stir in the drained crushed pineapple. If the frosting is too liquid, add more Cool Whip until reaching a desired consistency.
09 -
Spread the frosting evenly over the cooled cake. Refrigerate the cake for 2-3 hours to allow the frosting to set.
10 -
Slice the cake into 12 pieces while in the pan and garnish each slice with extra mandarin orange slices. Keep the cake refrigerated until serving.