01 -
Preheat the oven to 350°F. Spray a 9x13-inch baking dish with nonstick cooking spray.
02 -
Drain the can of mandarin oranges and reserve 1/2 cup of the juice, discarding the remaining juice.
03 -
Combine yellow cake mix, unsalted butter, mandarin orange juice, eggs, and vanilla extract. Beat for 3-4 minutes on medium-high speed.
04 -
Gently stir in the drained mandarin oranges, leaving some of the pieces 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. Cool completely.
06 -
Drain the can of crushed pineapple well and reserve 3/4 cup of the juice, discarding the rest.
07 -
In a bowl, mix the reserved pineapple juice with the vanilla instant pudding mix until combined.
08 -
Stir in powdered sugar and fold in the Cool Whip until fully combined.
09 -
Fold the drained crushed pineapple into the frosting mixture. If frosting is too runny, add more Cool Whip for a firmer consistency.
10 -
Spread the frosting over the cooled cake and refrigerate for at least 2-3 hours to allow the frosting to set.
11 -
Slice the cake into 12 pieces in the pan and top each slice with extra mandarin orange slices. Keep refrigerated until serving.