Place a 9x13 baking pan full of water on the bottom shelf of the oven. Leave the shelf above open for baking the cheesecake. Preheat oven to 325 and grease an 8" springform pan.
Mix together graham crackers and melted butter. Spread into the bottom of prepared pan and press firmly with the back of a spoon. Refrigerate while making the filling.
In a small bowl, add chocolate and butter.
Microwave the chocolate mixture for 1 minute on 50% power and stir well. Repeat, microwaving in 1 minute increments and stirring after each addition until completely melted and smooth.
Add cream cheese to a large mixing bowl and beat well. Pour in chocolate and beat well.
Add heavy cream, vanilla, sugar, cocoa powder and egg. Beat well, scraping down the sides halfway through.
Pour batter into pan, on top of crust. Smooth. Bake for 60-70 minutes or until there's about a 2" jiggly center.
Remove from oven and cool completely before refrigerating overnight.
Mix frosting together. Place into a piping bag fitted with a tip. Pipe onto the cheesecake. Slice to serve.