Prepare the Cake Batter: Preheat your oven to 350°F. In a large mixing bowl, combine the vanilla cake mix, eggs, milk (or vanilla almond milk), vegetable oil, and orange zest. Mixing until everything is smooth ensures a uniform batter that rises perfectly and bakes evenly.

Bake the Cake: Pour the batter into a greased 9x13-inch baking dish, spreading it out evenly. Bake in the preheated oven for 25 to 30 minutes until the cake is golden brown and a toothpick inserted in the center comes out clean.

Poke Holes in the Cake: Allow the cake to cool in the pan for 10 minutes after baking. Using a skewer or a fork, gently poke holes all over the top of the cake, about 1-inch apart.

Make the JELLO Mixture: In a small bowl, dissolve the orange JELLO in 1 cup of boiling water, stirring until completely dissolved. Then, add in ½ cup of fresh squeezed orange juice.

Pour the JELLO Over Cake: Slowly and carefully pour the JELLO mixture over the poked cake, allowing it to seep into the holes. Cover the cake and refrigerate for at least 3 hours.

Prepare the Frosting: In a mixing bowl, beat the canned mandarin oranges (with juice) and vanilla instant pudding mix together until well combined.

Frost the Cake: Once the cake has chilled, spread the mandarin orange frosting evenly over the top of the cake using a spatula.

Chill Before Serving: Refrigerate the frosted cake for at least another 30 minutes before serving.