1. Prepare the Crust

• Preheat your oven to 350°F (175°C).
• Crush the Oreos: Place the Oreo cookies in a food processor and pulse until finely ground. You want a fine crumb consistency.
• Mix with butter: Combine the ground Oreos with the melted butter. Stir until the mixture is moist and well-combined.
• Press into pan: Transfer the mixture into the bottom of a springform pan. Use the back of a spoon or your fingers to press it firmly into place, creating an even crust.
• Bake: Bake the crust in the preheated oven for 10 minutes, then remove and let it cool completely while you prepare the cheesecake filling.

2. Make the Cheesecake Filling

• Combine dry ingredients: In a large mixing bowl, sift together the cocoa powder and granulated sugar.
• Beat cream cheese: Add the room-temperature cream cheese to the bowl and beat with an electric mixer on medium speed until the mixture is smooth and free of lumps.
• Add chocolate: Mix in the melted bittersweet or semi-sweet chocolate until fully incorporated.
• Add wet ingredients: Pour in the heavy cream and vanilla extract, continuing to beat until smooth.
• Incorporate eggs: Add the eggs, one at a time, mixing thoroughly after each addition. This helps the eggs incorporate evenly into the batter.
• Add sour cream: Finally, add the sour cream and mix until everything is smooth and well combined.

3. Bake the Cheesecake

• Prepare for water bath: Wrap the bottom of your springform pan with aluminum foil to prevent leaks. Then, place the pan in a larger roasting pan.
• Add hot water: Carefully pour hot water into the roasting pan, filling it until it reaches halfway up the sides of the springform pan. This creates a steam effect that helps prevent the cheesecake from cracking.
• Bake: Place the pan in the oven and bake for 60-70 minutes. The cheesecake should be set around the edges, but the center should still be slightly jiggly when gently shaken.
• Cool gradually: Turn off the oven and crack the oven door open. Let the cheesecake cool in the oven for about 1 hour. This slow cooling process helps prevent cracking.
• Refrigerate: After the cheesecake has cooled in the oven, transfer it to the refrigerator and chill for at least 4 hours, or preferably overnight.

4. Create the Ganache

• Heat the cream: In a microwave-safe bowl, combine the milk chocolate chips and heavy cream. Microwave the mixture in 30-second intervals, stirring each time until the chocolate chips are melted and the mixture is smooth.
• Spread over cheesecake: Once the ganache is ready, spread it evenly over the chilled cheesecake, covering the top completely. Return the cheesecake to the refrigerator to allow the ganache to set, about 1 hour.

5. Finish with Chocolate Whipped Cream

• Heat cream: In a small saucepan, heat 2 tablespoons of heavy cream over medium heat until it just starts to simmer.
• Melt chocolate: Pour the simmering cream over the milk chocolate chips and stir until smooth. Let the mixture cool to room temperature.
• Whip the cream: In a large bowl, whip the remaining 1 cup of heavy cream until soft peaks form.
• Combine: Gradually add the cooled chocolate mixture to the whipped cream and continue whipping until stiff peaks form.
• Top the cheesecake: Pipe or spread the chocolate whipped cream over the top of the cheesecake.

6. Garnish

• Optional chocolate curls: If desired, garnish with chocolate curls to add an extra touch of elegance and a bit of texture.