In the mixing bowl of a stand mixer, add the butter, cream cheese, and vanilla, and blend with the whisk attachment until smooth and creamy.
Scrape down the sides of the bowl, and add 1 tablespoon of the heavy cream, and blend until smooth.
Add the powdered sugar 1 cup at a time, blending between additions, and scraping the bowl down as needed.
When all the powdered sugar has been added, add the remaining tablespoon of heavy cream, and add the cocoa a little at a time, until all the cocoa is added, and the frosting is blended smooth.
Scrape down the bowl, and blend one more time, making sure the frosting is smooth and creamy.
Remove the chilled cake from the refrigerator, and frost the cake with the chocolate Frosting.
Place the cake back in the refrigerator until time to serve.
Cut in 3 inch pieces, serve, and Enjoy!