Preheat your oven according to the instructions on your cake mix box. Grease a 9×13-inch baking dish and set aside.

In a large bowl, combine the cake mix, eggs, milk, oil, and orange zest. Mix according to package directions until smooth and well blended.

Pour the batter into the prepared pan and bake as directed on the box. Baking times may vary slightly based on your oven and cake mix brand.

Once the cake is baked, remove it from the oven and let it cool for about 10 minutes. It should still be warm, but not hot.

Using a wooden skewer or fork, poke holes all over the top of the cake. Make sure to reach about halfway through the cake so the Jello soaks in evenly.

In a separate heatproof bowl, add the orange Jello powder. Pour in the boiling water slowly and whisk until completely dissolved.

Stir in the fresh orange juice. Let the mixture cool for a minute, then slowly pour it over the cake, making sure to cover it evenly.

Place the cake in the refrigerator and chill for at least 3 hours. This helps the Jello set and infuse the cake with flavor.

To make the frosting, blend the mandarin oranges and vanilla pudding mix in a medium bowl. Beat until smooth and well combined.

Gently fold in the Cool Whip until the frosting is light and fluffy. Spread it over the cooled cake in an even layer.

Refrigerate the finished cake for at least 30 minutes before serving. Garnish with extra mandarin oranges or a sprinkle of zest if you’d like.