01 - Preheat oven to 350°F. Grease a 9x13-inch baking pan thoroughly.
02 - Combine yellow cake mix, eggs, crushed pineapple with juice, vegetable oil, and water in a large bowl. Beat until batter is smooth and well blended, about 2 minutes.
03 - Pour batter into prepared pan. Bake for 28-32 minutes or until a toothpick inserted in the center comes out clean.
04 - Let cake cool in pan for 10 minutes. Using the handle of a wooden spoon, poke holes evenly across the entire cake surface, spacing about 1 inch apart.
05 - Whisk together sweetened condensed milk and coconut milk in a medium bowl until completely smooth and combined.
06 - Slowly pour the milk mixture evenly over the warm cake, ensuring liquid fills all the holes. Allow to absorb for 5 minutes.
07 - Whisk together instant vanilla pudding mix, cold milk, and pineapple juice in a separate bowl. Continue whisking until mixture begins to thicken, about 2 minutes.
08 - Spread the thickened pudding mixture evenly over the cake, filling the holes and creating a smooth layer on top.
09 - Cover pan with plastic wrap or foil. Refrigerate for at least 1 hour until completely chilled and set.
10 - Once chilled, spread the thawed whipped topping evenly over the entire surface of the cake.
11 - Sprinkle toasted coconut evenly over the top. Garnish with fresh pineapple chunks and maraschino cherries if desired. Slice into 12 servings and serve cold.