Prepare the crust by positioning a rack in the middle of the oven and preheating it to 350°F. Grease a 9½-inch deep-dish pie pan or a 9-inch springform pan with cooking spray, then place the pan on a baking sheet. Melt 6 tablespoons of unsalted butter using either the microwave or stovetop. Place 24 Oreos into a food processor bowl fitted with a blade attachment and pulse until finely ground, about 30 seconds, yielding roughly 2 heaping cups. Add the melted butter and ½ teaspoon kosher salt, then pulse 10 to 12 times in one-second intervals until the mixture resembles wet sand and holds together when pinched. Transfer this mixture into the prepared pan and use a flat-bottomed measuring cup to press it firmly into the bottom and about ½ inch up the sides, avoiding the full height of the pan. Bake the crust for 8 to 10 minutes until the center no longer looks wet, then remove and cool on a wire rack while preparing the brownie base.

To make the brownie base, place 4 tablespoons unsalted butter in a large microwave-safe bowl and melt on high for 40 to 50 seconds. Add ¼ cup granulated sugar and ¼ cup packed brown sugar, whisking until the sugars are fully incorporated. Stir in 1 large egg, ¼ cup Dutch-processed cocoa powder, 1 teaspoon vanilla extract, and ¼ teaspoon kosher salt until smooth. Then add ¼ cup all-purpose flour and ⅛ teaspoon baking powder, whisking just until combined with no visible flour streaks. Spread the batter evenly over the cooled crust and bake for 20 to 27 minutes, or until a toothpick inserted into the center comes out with a few moist crumbs. Allow it to cool completely for 1 to 2½ hours.

For the chocolate filling, whisk together one 3.9-ounce box of instant chocolate pudding mix in a large bowl to break up any clumps. Gradually add 2 cups whole or 2% milk and whisk vigorously until thick and smooth, about 1 to 2 minutes. Pour this pudding evenly over the cooled brownie base, smoothing the surface. Cover with plastic wrap pressed directly onto the pudding to prevent a skin from forming, and refrigerate for at least 2 hours or overnight.

To garnish, chop or crush 4 Oreos into pieces no larger than peas. When ready to serve, whip 1½ cups cold heavy cream, ¼ cup powdered sugar, and ½ teaspoon vanilla extract in a stand mixer bowl or a large mixing bowl using an electric hand mixer. Beat on medium speed with the whisk attachment until firm peaks form, about 2 to 5 minutes. Spread the whipped cream evenly over the pie, smoothing the top with an offset spatula. Sprinkle with the crushed Oreos and, if desired, 2 tablespoons of chocolate curls. If using a pie pan, slice and serve directly from the pan. For a springform pan, run a knife or offset spatula around the edges, release and remove the ring, then slice and serve.