Ugh, you can just tell from the photos how rich and moist this chocolate cake is. You can obviously decorate it however you want, but I wanted this cake to just scream chocolate at you so that's why I added the candy bars on top, totally optional.
Preheat the oven to 350 degrees. Grease two 9 inch round cake pans and line the bottoms with parchment paper. Set aside.
Sift together the cocoa powder and cake flour into the bowl of a stand mixer. Add the sugar, baking soda, and salt. Stir to combine with the paddle attachment. Add the eggs, butter, cream cheese, and vanilla until combined. Scrape the sides as needed.
Take the bowl off the mixer and stir in the water and chocolate chips by hand until smooth. Evenly divide batter between the two cake pans. Bake for 20-25 minutes until a toothpick inserted into the center comes out clean. A few crumbs are okay, but any wet batter means it needs to bake longer.
Place on wire rack to cool for 15 minutes. Take out cakes and let cool completely on the wire rack.
In the bottom of a stand or hand mixer, cream the butter until smooth. Whisk together the cocoa powder and powdered sugar, slowly add into the butter a little at a time until incorporated. Scrape the sides as needed.
Add the heavy cream one tablespoon at a time so it doesn't splatter. Add the vanilla and whip on medium speed for 3 minutes until light and fluffy. Stir in the melted chocolate until combined.
On the decorating surface of your choice, add about a tablespoon dollop of frosting on the center. Place one of the chocolate cakes top side up. Add 1/3 of the frosting and smooth over with a spatula.
Add the second cake on top, top side down so the top will be level. Add a thin crumb coat all over the cake. Pay attention to the sides where the cake comes together if there is a gap fill it in completely. Place in fridge for 30 minutes to set.
Add another thicker layer of frosting to the cake, decorate as desired, cut, and enjoy!