Step 1: Prepare the Crust
1. Mix Crust Ingredients: In a medium bowl, combine the crushed chocolate cookies and melted butter. Mix until the crumbs are evenly coated.
2. Press into Pan: Press the mixture firmly into the bottom of a 9×9-inch (or similar size) square baking dish. Use the back of a measuring cup to pack it down tightly.
3. Chill: Place the crust in the refrigerator while you prepare the filling.

Step 2: Make the Cheesecake Filling
1. Beat Cream Cheese: In a large mixing bowl, beat the softened cream cheese with an electric mixer until smooth and creamy.
2. Add Sugar and Vanilla: Gradually add the powdered sugar and vanilla extract, mixing until well combined.
3. Whip Cream: In a separate bowl, whip the heavy cream until stiff peaks form.
4. Combine Mixtures: Gently fold the whipped cream into the cream cheese mixture until fully incorporated. Be careful not to deflate the whipped cream.
5. Add Cocoa and Chocolate: Sift in the cocoa powder and fold it in gently. Then, add the melted chocolate chips and mix until smooth and creamy.

Step 3: Assemble the Bars
1. Spread Filling: Pour the cheesecake filling over the chilled crust and spread it evenly with a spatula.
2. Chill: Cover the pan with plastic wrap and refrigerate for at least 4 hours, or until set.

Step 4: Make the Ganache
1. Heat Cream: In a small saucepan, heat the heavy cream over medium heat until it just begins to simmer.
2. Add Chocolate Chips: Remove from heat and add the chocolate chips. Let it sit for a minute, then stir until smooth and glossy.

Step 5: Finish the Bars
1. Pour Ganache: Once the cheesecake has set, pour the chocolate ganache over the top, spreading it evenly.
2. Chill Again: Return the bars to the refrigerator for an additional 30 minutes to allow the ganache to set.

Step 6: Serve
1. Cut into Bars: Once set, remove the cheesecake from the pan and cut it into squares or bars.
2. Garnish: Optional: Top with whipped cream, chocolate shavings, or additional crushed cookies before serving.