Make the Crust: Pulse whole Oreos in a food processor until fine crumbs form. Mix with melted butter. Press into the bottom and halfway up the sides of a 9-inch springform pan. Refrigerate.
Preheat Oven: Set oven to 325°F.
Prepare Cheesecake Filling: Beat softened cream cheese in a bowl until smooth and fluffy. Add eggs one at a time, mixing after each. Stir in sugar and vanilla, scraping the bowl as needed.
Add Oreos: Gently fold in chopped Oreo chunks.
Assemble: Pour the filling into the prepared Oreo crust.
Bake: Bake for 60-70 minutes, until the edges are set and the center is slightly soft but not jiggly. Cool completely.
Make Ganache: Heat butter and cream in a saucepan until simmering. Pour over chocolate in a bowl and stir until smooth. Add vanilla and powdered sugar.
Top with Ganache: Spread ganache evenly over the cooled cheesecake. Refrigerate for at least 1 hour before serving.