Bake the yellow cake in a 9”x13” sheet cake pan according to the directions on the box and let it cool completely.
When the cake is cooled, loosen the edges with a butter knife and cut the cake into 24 serving size pieces. With a skewer or butter knife, poke holes all over the cake making sure the holes reach down to the bottom of the cake. Also, take the handle of a wooden spoon and poke a bigger hole in the center of each slice of cake.
With a handheld mixer, mix the coconut milk, sweetened condensed milk, half and half and vanilla extract together until combined and smooth, about 1-2 minutes.
Slowly pour the milk mixture over the cake, only pouring about ⅓ of the milk at a time and letting it soak in between. When it begins to pool on top of the cake, let it sit for a few minutes before pouring the rest of the milk mixture on top. It’s ok if it all does not absorb right away. It will continue to soak in the milk as it sits in the fridge.
Chill the cake in the fridge (covered) for at least 8 hours. You can chill it up to 2 days ahead of time before serving.
Toast the sweetened coconut flakes in a non-stick skillet for 3-4 minutes on med heat until they become fragrant and begin to brown. Remove it from the heat.
Before serving the cake, cover it completely and evenly with whipped topping and sprinkle the toasted coconut flakes on top. Enjoy!