In a food processor, crush the Oreos till they become a fine crumb. Add melted butter, stirring until fully combined.
Press into the bottom of the prepared pan, use a cup to tightly press the crumbs into place. Bake for 5 minutes then set aside while you prepare the filling.
Beat cream cheese for 2 minutes on medium to high speed. You want a smooth, creamy texture with no lumps.
Beat Cream Cheese
Add granulated sugar and sift cocoa powder in then beat for another minute.
Sift in Cocoa Powder
Add in melted chocolate, sour cream, heavy cream, & vanilla mixing until combined- make sure to scrape the bottom of the bowl.
Add More Ingredients
Add in eggs and yolk one at a time, and mix until just combined. You should have a creamy batter with no lumps.
Pour on top of the crust and use a spatula to spread into an even layer.
Bake until the middle of the cheesecake should jiggle just a little bit. Cool and then chill the cheesecake.
Slice and top with fresh whipped cream and grate chocolate shavings on top.