1. Prepare Pan and Make Oreo Crust:

• Lightly spray the bottom and sides of a 9-inch springform pan with nonstick cooking spray.
• Place whole Oreos in a food processor and pulse until fine crumbs form. (Alternatively, crush in a sealed bag with a rolling pin).
• Add the melted butter to the Oreo crumbs and pulse or stir until the crumbs are evenly moistened, resembling wet sand.
• Transfer the crumbs to the prepared springform pan. Press firmly onto the bottom and evenly up the sides of the pan using the bottom of a measuring cup or glass.
• Place the crust in the refrigerator to chill and firm up for at least 30 minutes while you prepare the first ganache layer.

2. Make and Add Ganache Layer:

• Place the 1 cup of semi-sweet chocolate chips (chopped slightly if large) in a medium heatproof bowl.
• Heat the ⅓ cup of heavy whipping cream in a microwave-safe container (or small saucepan) in 30-second increments on high, just until the cream begins to simmer.
• Pour the hot cream over the chocolate chips. Gently stir to ensure all chocolate is covered. Let the mixture sit undisturbed for 2-3 minutes to allow the chocolate to melt.
• Gently whisk the cream and chocolate together until the ganache is completely smooth, glossy, and homogeneous.
• Pour this ganache over the chilled Oreo crust in the springform pan. Use an offset spatula to spread it into an even layer covering the crust.
• Return the pan to the refrigerator to chill for another 30 minutes, allowing the ganache layer to set slightly.

3. Prepare the Cheesecake Filling:

• Whip Cream: In a medium bowl (preferably chilled), beat the ½ cup of cold heavy whipping cream with an electric mixer until stiff peaks form. Set aside.
• Beat Cream Cheese Base: In a separate large bowl, beat the softened cream cheese with the electric mixer on medium-high speed for 2 to 3 minutes until completely smooth, light, and fluffy. Scrape down the sides of the bowl.
• Beat in the sifted powdered sugar on low speed until combined, then increase speed briefly until no lumps remain.
• Beat in the room temperature sour cream and vanilla extract until just combined.
• Combine: Gently fold the previously whipped cream into the cream cheese mixture using a rubber spatula until just combined and no streaks remain. Be careful not to deflate the whipped cream.
• Fold in the 1 cup of mini chocolate chips.

4. Assemble Cheesecake:

• Remove the chilled crust/ganache layer from the refrigerator.
• Pour the prepared chocolate chip cheesecake filling over the set ganache layer in the springform pan.
• Spread the filling into an even layer using an offset spatula or the back of a spoon.

5. Chill Thoroughly:

• Cover the springform pan carefully with plastic wrap (try not to let it touch the filling surface).
• Refrigerate the cheesecake for at least 4 hours, or preferably overnight (6-8 hours), until the cheesecake filling is completely firm and set. This is crucial for a no-bake recipe.

6. Make Ganache Topping and Decorate:

• Once the cheesecake is fully chilled and set, prepare the topping ganache. Place the ⅓ cup chocolate chips in a small heatproof bowl.
• Heat the 2 tbsp heavy whipping cream until just simmering (microwave or stovetop).
• Pour the hot cream over the chips, let sit 2-3 minutes, then whisk gently until smooth and glossy.
• Let the topping ganache cool slightly so it’s still pourable but not hot.
• Carefully run a thin knife around the edge of the cheesecake and release the springform pan sides.
• Drizzle the topping ganache decoratively over the top of the chilled cheesecake, letting it drip down the sides if desired.

7. Final Chill and Serve:

• Return the cheesecake to the refrigerator for about 15-30 minutes to allow the ganache drizzle to set.
• Keep the cheesecake refrigerated until ready to serve. Slice using a large, sharp knife dipped in hot water and wiped clean between cuts. Serve chilled.