Preheat your oven to 350°F (175°C) and line a 12-cup muffin pan with cupcake liners.

In a mixing bowl, combine Oreo crumbs and melted butter. Press into the bottom of each muffin liner. Bake for 5 minutes and cool.

Melt bittersweet or semisweet chocolate in a microwave-safe bowl until smooth.

Beat cream cheese, granulated sugar, and cocoa powder until creamy. Mix for about 2-3 minutes.

Blend in sour cream, heavy cream, and vanilla until smooth. Slowly add melted chocolate and mix until combined.

Add eggs one at a time, mixing gently after each addition. Scrape down the bowl as needed.

Fill each muffin liner with cheesecake batter, bake for 18-20 minutes until puffed, then cool on a wire rack.

Heat heavy whipping cream for ganache until it boils. Pour over dark chocolate chips and stir until smooth.

Whip heavy cream with powdered sugar, cocoa powder, and vanilla until stiff peaks form.

Spoon ganache over cooled cheesecakes and top with whipped cream. Add chocolate truffles if desired.