1. Crush Oreo cookies into fine crumbs and mix with melted butter.
2. Press the mixture into the bottom of a springform pan to form the crust.
3. In a large bowl, beat cream cheese until smooth and creamy.
4. Add peanut butter, powdered sugar, and vanilla extract, then mix until well combined.
5. In a separate bowl, whip heavy cream until stiff peaks form.
6. Gently fold whipped cream into the peanut butter mixture to keep it light and airy.
7. Spread the filling evenly over the Oreo crust, smoothing the top with a spatula.
8. Cover and refrigerate for at least 6 hours or overnight to set properly.
9. Prepare chocolate ganache by melting chocolate with warm heavy cream, then let it cool slightly.
10. Pour the ganache over the set cheesecake and spread evenly.
11. Optionally, drizzle with melted peanut butter and sprinkle with chopped peanuts or chocolate chips.
12. Let the ganache set in the refrigerator for at least 30 minutes before serving.
13. Remove from the pan, slice, and enjoy the rich, creamy, mousse-like cheesecake.
14. Store leftovers in the refrigerator for up to 5 days or freeze for longer storage.