01 - Preheat oven to 350°F. Grease a 9x13-inch baking pan thoroughly with cooking spray or butter.
02 - In a large mixing bowl, combine yellow cake mix, eggs, crushed pineapple with juice, vegetable oil, and water. Beat with electric mixer on medium speed until completely smooth, about 2 minutes.
03 - Pour batter into prepared baking pan. Bake for 28-32 minutes until golden brown and 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 all over the surface of the warm cake, spacing approximately 1 inch apart in a grid pattern.
05 - In a medium bowl, whisk together sweetened condensed milk and coconut milk until thoroughly combined and smooth.
06 - Slowly pour the milk mixture evenly over the warm cake, ensuring it soaks into the poked holes. Allow to absorb for 5 minutes.
07 - In a separate bowl, whisk instant vanilla pudding mix with cold milk and reserved pineapple juice. Continue whisking for 2 minutes until pudding begins to thicken.
08 - Spread the thickened pudding 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 - Remove cake from refrigerator. Spread whipped topping evenly over the entire surface of the chilled cake.
11 - Sprinkle toasted coconut generously over the whipped topping. Garnish with fresh pineapple chunks and maraschino cherries if desired.
12 - Slice into 12 equal squares and serve cold. For best results, serve immediately after topping or keep refrigerated until serving.