Preheat the oven to 350°F and butter a 9x13-inch baking dish.
In a large mixing bowl, combine the white cake mix, eggs, and buttermilk. Beat until smooth and well combined.
Pour the batter into the prepared baking dish and spread it evenly.
Bake for 25 minutes, but start checking at 20 minutes. The cake is done when the top is golden and a toothpick comes out clean.
While the cake is baking, make the coconut cream filling: In a medium bowl, whisk together coconut cream, sweetened condensed milk, and buttermilk until smooth.
Once the cake is out of the oven and still warm, use a fork to poke holes all over the surface of the cake.
Slowly pour the coconut cream mixture over the warm cake, making sure it seeps into the holes.
Cover the cake and refrigerate for at least 2 hours or overnight to allow the flavors to soak in.
When ready to serve, spread a layer of thawed Cool Whip evenly over the top of the chilled cake.
Sprinkle generously with sweetened shredded coconut (you can toast it for extra flavor!).
Slice, serve, and enjoy every dreamy, coconut-soaked bite!