Preheat your oven to 350°F (175°C). Grease and flour two 9-inch round cake pans thoroughly, then line the bottoms with parchment paper for easy removal after baking.

In a large mixing bowl, combine the yellow cake mix, 8 ounces of crushed pineapple (with juice), vegetable oil, eggs, and vanilla extract. Beat on medium speed for about 2 minutes until the batter is smooth and light.

Divide the batter evenly between the two prepared pans. Tap the pans gently on the counter to release any air bubbles. Bake for 25–30 minutes, or until a toothpick inserted into the center comes out clean. The cakes should be golden and slightly springy to the touch.

Let the cakes cool in their pans for 10 minutes. Then turn them out onto wire racks, peel off the parchment, and allow them to cool completely before frosting—this is key to avoid melting the frosting.

In a medium bowl, stir together the instant vanilla pudding mix and the second can of crushed pineapple (with juice). Once combined and thickened, gently fold in the thawed whipped topping until smooth and creamy.

Place one cake layer on your serving plate. Spread a thick layer of the pineapple-pudding mixture across the top. Place the second layer gently on top, aligning the edges. Use the remaining frosting to cover the top and sides of the cake evenly.

Garnish with pineapple slices, cherries, or a sprinkle of toasted coconut if you like a festive tropical look. You can press the coconut around the sides for extra texture.

Place the finished cake in the refrigerator for at least 1 hour before slicing. This helps it set up for clean, neat slices and allows the flavors to meld.