Preheat the oven to 350°F and prepare a 9x13 inch baking pan with a light coating of cooking spray. Set aside.
In a large bowl, combine cake mix, water, vegetable oil, and eggs. Mix until thoroughly combined.
Pour batter into the prepared baking pan and bake for 30-35 minutes or until a toothpick inserted in the center comes out clean. Remove from oven and let cool for about 20 minutes.
Poke holes all over the cake.
Place the condensed milk and 1/4 cup chocolate chips in a microwave-safe bowl. Microwave in 30-second intervals, whisking until smooth and combined.
Pour chocolate mixture over the cake, using a rubber scraper to fill the holes.
Chill cake in the fridge for an hour.
To make the frosting, combine Cool Whip with cocoa powder. Spread whipped topping on top of the cake.
Top cake with chocolate chips, chocolate shavings & drizzle with chocolate sauce. Let chill again for about 1 hour. Enjoy!