Preheat the oven to 375 degrees.
In a bowl, combine the crushed Oreo cookies, sugar, and melted butter. Mix until a thick paste forms.
Grease an 8-inch round pan with butter or nonstick spray and press the Oreo cookie mixture into it, forming the bottom layer of your cheesecake.
In a separate bowl, mix together the cream cheese, vanilla extract, and cocoa until fully combined.
Spread the cream cheese mixture over the Oreo crust layer, using an offset spatula to evenly distribute it.
Top with the whipped topping and spread it out so that it covers the entire surface of the cheesecake.
Garnish with Oreo cookies. Place in a preheated oven and bake for 25-30 minutes, or until a toothpick inserted into the center comes out clean.
Let it cool before serving.