Step 1: Preheat the oven
Preheat your oven to 350°F (175°C) and lightly grease a 9×13-inch baking dish.

Step 2: Mix the cake batter
In a large mixing bowl, combine the yellow cake mix, undrained crushed pineapple, eggs, and vegetable oil. Mix with a hand mixer or whisk until well combined and smooth.

Step 3: Bake the cake
Pour the batter into the prepared baking dish and spread evenly. Bake for 30–35 minutes or until a toothpick inserted in the center comes out clean. Let it cool completely before adding the topping.

Step 4: Make the topping
In another bowl, combine the instant vanilla pudding mix and the second can of crushed pineapple (with juice). Stir until the pudding mix is dissolved and the mixture thickens slightly.

Step 5: Fold in whipped topping
Gently fold in the whipped topping until fully combined, forming a fluffy, fruity topping.

Step 6: Frost the cake
Once the cake has completely cooled, spread the pineapple-pudding-whipped topping mixture evenly over the top.

Step 7: Chill and serve
Refrigerate for at least 1 hour before slicing and serving. For best results, chill for 2–3 hours to allow flavors to meld and texture to firm up.