In a large bowl, I mix the cake mix and orange gelatin until evenly combined. Then I add eggs, oil, orange juice, and zest, mixing until smooth. The batter should look thick but pourable, with a vibrant orange color.
I pour the batter into a greased 9×13-inch pan and level the top gently. The cake bakes at 350°F (175°C) for about 30 minutes. I check doneness by inserting a toothpick into the center—it should come out clean.
Once baked, I let the cake cool in the pan for about 20 minutes. After that, I leave it at room temperature until fully cooled. This step is important so the frosting doesn’t melt or slide off.
In a bowl, I whisk the pudding mix, milk, and vanilla extract until thickened. Then I gently fold in the whipped topping until fluffy and smooth. The frosting should be light, creamy, and easy to spread.
I spread the frosting evenly over the cooled cake using a spatula. After frosting, I refrigerate the cake for at least 1 hour. Chilling helps the flavors blend and gives clean, neat slices.