Preheat the oven according to the cake mix package directions and grease a 9x13-inch baking dish.
Prepare the chocolate cake batter following the package instructions. Pour the batter into the prepared baking dish and bake until a toothpick inserted into the center comes out clean.
Remove the cake from the oven and allow it to cool for about 10 minutes. While the cake is still warm, use the handle of a wooden spoon or a large straw to poke holes all across the surface of the cake. Make sure the holes go deep into the cake so the filling can soak in well.
In a medium bowl, whisk together the sweetened condensed milk, cream of coconut, and coconut extract until smooth and fully combined.
Slowly pour the coconut mixture evenly over the warm cake, allowing the filling to soak into all the holes. Spread gently if needed so the mixture reaches every part of the cake.
Let the cake cool completely at room temperature, then refrigerate for at least 2 hours so the flavors can blend and the cake becomes extra moist and creamy.
Once chilled, spread the whipped topping evenly over the entire cake using a spatula to create a fluffy layer.
Sprinkle the toasted shredded coconut generously over the whipped topping. If desired, add light swirls of chocolate pudding or drizzle chocolate sauce over the top for extra richness.
Slice into squares and serve chilled for the best flavor and texture.