01 - Preheat oven to 350°F and 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 completely smooth and well incorporated.
03 - Pour batter into prepared baking pan. Bake for 28-32 minutes until a toothpick inserted into the center emerges clean.
04 - Allow cake to cool for 10 minutes. Using the handle of a wooden spoon, poke holes evenly across the entire cake surface, spacing approximately 1 inch apart.
05 - Whisk together sweetened condensed milk and coconut milk in a medium bowl until fully blended. Drizzle this mixture slowly and evenly over the warm cake, allowing it to absorb into the holes.
06 - Combine instant vanilla pudding mix, cold milk, and pineapple juice in a separate bowl. Whisk vigorously for approximately 2 minutes until pudding thickens noticeably. Spread evenly over the cake surface.
07 - Cover the pan with plastic wrap or aluminum foil. Refrigerate for a minimum of 1 hour, though 2-3 hours yields optimal texture and flavor development.
08 - Once cake is thoroughly chilled, spread the thawed whipped topping evenly across the entire surface using a spatula.
09 - Sprinkle toasted coconut flakes generously over the whipped topping. Arrange fresh pineapple chunks and maraschino cherries across the top as desired.
10 - Cut into 12 equal portions and serve cold. For best results, slice with a clean knife dipped in hot water between cuts.