Preheat your oven to 350°F (175°C).

Grease and flour three 9-inch round cake pans. This ensures the cakes do not stick to the pans and can be easily removed after baking.

In a large mixing bowl, combine the yellow cake mix, eggs, and vegetable oil.

Use an electric mixer on medium speed to beat the mixture until everything is well combined and smooth. This usually takes about 2 minutes.

The batter will be thick initially, but continue mixing until it becomes smooth and creamy.

Open the can of mandarin oranges and pour the entire contents, including the juice, into the cake batter.

Continue mixing with the electric mixer on medium speed. The mixer will help break up the mandarin oranges into smaller pieces and distribute them evenly throughout the batter.

Mix until the oranges are well incorporated and the batter has a consistent texture with no large chunks of fruit.

Divide the batter equally between the three prepared pans. You can use a measuring cup or a kitchen scale to ensure equal distribution.

Place the cake pans in the preheated oven and bake for 20 to 25 minutes. Start checking for doneness around the 20-minute mark by inserting a toothpick into the center of each cake layer. If it comes out clean with no batter clinging to it, the cakes are done.

Avoid opening the oven door too frequently during baking, as this can cause the cakes to sink. Only check for doneness towards the end of the baking time.

Once the cakes are baked, remove them from the oven and place them on wire racks to cool for about 10 minutes.

After 10 minutes, gently run a knife around the edges of each cake layer to loosen them from the pans.

Carefully invert the pans onto the wire racks and lift them off to release the cakes.

Allow the cakes to cool completely on the wire racks before frosting. Cooling completely is important to prevent the frosting from melting when applied to the warm cakes.

In a medium mixing bowl, combine the thawed Cool Whip, instant vanilla pudding mix, and crushed pineapple with its juice.

Use a spoon or spatula to mix the ingredients together until they are thoroughly combined and the frosting is smooth. The pudding mix will help stabilize the frosting and give it a creamy texture.

Place one of the fully cooled cake layers on a serving plate or cake stand.

Spread a generous layer of frosting evenly over the top of the cake layer using a spatula or the back of a spoon.

Carefully place the second cake layer on top of the frosted first layer.

Repeat the process by adding another layer of frosting on top of the second cake layer.

Finally, place the third cake layer on top and frost the top and sides of the entire cake with the remaining frosting. Use long, smooth strokes with the spatula to create an even and polished finish.

Refrigerate the assembled cake for at least an hour before serving. Chilling allows the flavors to meld together and the frosting to set properly, making it easier to slice and serve.

Store any leftover cake in the refrigerator, covered, to keep it fresh.