Preheat your oven to 350°F (175°C) and lightly spray a 9x13 inch baking dish. This prepares your canvas!
In a large bowl, combine the cake mix, undrained crushed pineapple, vegetable oil, and eggs. Beat with a hand mixer on low speed for about 30 seconds, then increase to medium and mix for 2 more minutes until the batter is smooth.
Pour the cake batter into your prepared dish, spreading it out evenly. Bake for 28 to 33 minutes, or until a toothpick inserted into the center comes out clean.
Let the baked cake cool on a wire rack for 30 minutes. Once slightly cooled, gently poke holes all over the top of the cake using a fork. Try not to crumble the top too much!
While your cake cools, whisk together the cream of coconut, pineapple juice, and rum extract in a medium bowl until nicely blended.
Slowly and carefully pour the tropical filling over the poked cake, allowing it to seep into all the holes. Let the cake continue to cool completely and absorb all the delicious liquid – this makes it incredibly moist!
In another large bowl, combine the pudding mix and milk. Whisk for about 2 minutes until the mixture thickens.
Gently fold in the thawed whipped topping until there are no streaks. Then, add the well-drained crushed pineapple and fold it into the mixture until evenly combined.
Carefully spread the fluffy frosting over the completely cooled cake. For an extra touch of flavor and healthy fats, sprinkle with toasted coconut if you like.
Cut into squares and serve this refreshing cake! Store any leftovers in an airtight container in the fridge for up to 4 days.