Add the 24 Oreo cookies (filling included) to a food processor and pulse until they form fine, even crumbs. Pour the 6 tablespoons of melted butter over the crumbs and pulse or stir until the mixture looks like wet sand and holds together when pressed between your fingers. Transfer to a 9 inch pie dish and press firmly and evenly across the bottom and up the sides using the bottom of a measuring cup.
Place the pressed crust in the freezer for 15 to 20 minutes, or in the refrigerator for 30 minutes, until it feels firm to the touch.
Place the 12 ounces of semisweet chocolate chips in a heatproof mixing bowl. In a medium saucepan, heat the 1 1/2 cups of heavy cream over medium heat until it just starts to steam and small bubbles form around the edge. Pour the hot cream over the chocolate chips and let sit undisturbed for 2 to 3 minutes. Add the 2 tablespoons of butter, 1 teaspoon of vanilla extract, and a pinch of salt, then whisk slowly until smooth and glossy.
Pour the warm chocolate ganache into the chilled Oreo crust. Use a spatula to spread it into an even layer, making sure it reaches all the way to the edges. Gently tap the pie dish on the counter a few times to release any air bubbles.
Cover the pie loosely with plastic wrap, being careful not to let the wrap touch the ganache. Refrigerate for at least 3 hours, or until the filling is completely set and no longer jiggles in the center.
Once the pie has fully set, add the remaining 1 cup of heavy cream, 3 tablespoons of powdered sugar, and the remaining 1/2 teaspoon of vanilla extract to a cold mixing bowl. Using a hand mixer on medium high speed, whip for 2 to 3 minutes until stiff peaks form.
Spread or pipe the whipped cream over the top of the chilled pie, leaving a small border of chocolate visible around the edge. If using, run a vegetable peeler along the edge of a chocolate bar to create curls, then scatter them over the whipped cream.
Dip a sharp knife in hot water and wipe it dry before each slice for the cleanest cuts through the ganache layer. Serve the pie cold, straight from the refrigerator.