Begin by preparing the cake mix. In a large mixing bowl, combine the vanilla cake mix with 3 eggs, 1 cup of milk (or vanilla almondmilk), ½ cup of vegetable oil, and 1 tablespoon of orange zest. Mix until well combined, according to the package instructions for a 9x13 inch pan. You’ll want a smooth batter with no lumps, so take your time mixing it evenly.
Once your batter is ready, preheat the oven to the temperature specified on the cake mix package. Pour the batter into the prepared pan and bake for the recommended time, usually about 25 to 30 minutes, or until a toothpick inserted in the center comes out clean. When done, remove the cake and allow it to cool on a wire rack for about 10 minutes.
While the cake is cooling, prepare the orange JELLO mixture. In a heat-proof bowl, dissolve the orange JELLO mix in 1 ¼ cups of boiling water, whisking until fully dissolved. This should take just a couple of minutes. Next, stir in ⅓ cup of fresh squeezed orange juice to enhance that vibrant orange flavor you'll love in this Orange Creamsicle Cake.
Once the cake has cooled, it's time to poke some holes! Use a skewer or a fork to gently poke holes all over the surface of the cake. Be sure to space them evenly to allow the JELLO to penetrate throughout. Slowly and carefully pour the prepared JELLO mixture over the cake, ensuring that it seeps into all the holes you've made, creating that delightful moist texture.
Cover the cake with plastic wrap and refrigerate it for at least 3 hours, or until the JELLO is fully set. This chilling time is crucial for the flavors to meld and for the cake to absorb that luscious orange goodness, making it a truly refreshing Orange Creamsicle Cake.
As your cake chills, prepare the frosting. In a mixing bowl, combine the undrained mandarin oranges and the vanilla instant pudding mix. Stir until well combined, then gently fold in 8 ounces of Cool Whip until everything is nicely incorporated. The mix will be light and fluffy, a perfect topping for your cake!
Finally, take the cake out of the fridge and spread the fluffy orange frosting evenly over the top. Make sure to cover it nicely, as this will be the crowning touch to your Orange Creamsicle Cake. Return the cake to the refrigerator for about 30 minutes to let the frosting set slightly before serving. Enjoy each refreshing bite!