Step 1: Prepare the crust
Crush the Oreos into fine crumbs using a food processor. Combine the crumbs with melted butter until the mixture resembles wet sand. Press it firmly into a parchment-lined 8×8-inch pan to form an even base. Chill in the refrigerator while preparing the filling.

Step 2: Make the filling
In a large bowl, beat the softened cream cheese and granulated sugar until smooth and creamy. Add the vanilla extract and melted chocolate, mixing until fully incorporated. Fold in the whipped topping gently using a spatula until the mixture is light and fluffy.

Spread the cheesecake filling evenly over the chilled crust. Smooth the top with an offset spatula. Return to the refrigerator and chill for at least 2 hours or until firm.

Step 3: Make the ganache
Heat the heavy cream in the microwave or on the stovetop until steaming but not boiling. Pour it over the chocolate chips in a bowl. Let sit for 2–3 minutes, then stir until smooth. Allow the ganache to cool slightly before pouring over the chilled cheesecake layer.

Spread the ganache evenly and return to the refrigerator to chill for another hour, or until fully set.

Step 4: Slice and serve
Once fully chilled and firm, lift the bars out of the pan using the parchment paper. Slice into squares and top with optional garnishes like chocolate shavings or crushed cookies.