Pulse the Oreos in a food processor until you have fine, even crumbs. In a medium size bowl, stir in the melted butter and crushed oreos until the mixture resembles wet sand and holds together when pressed. Press firmly and evenly into the bottom and up the sides of a 9-inch pie dish using the bottom of a measuring cup. Refrigerate while you make the filling.
26 Oreos, 6 tablespoon salted butter
In a large bowl, whisk together the egg yolks, sugar, cornstarch, cocoa powder, and salt. It will look like a thick brownie batter. Set aside.
½ cup granulated sugar, ¼ cup cocoa powder, ¼ teaspoon kosher salt, ¼ cup corn starch, 6 egg large egg yolks
Heat the milk and cream in a medium saucepan over medium heat until steaming and just barely simmering. Do not boil. Remove from heat.
2 cups whole milk room temperature, ½ cup heavy cream
Whisking constantly, slowly pour about ½ cup a the hot milk and cream mixture into the chocolate egg mixture in a thin, steady stream, whisking constantly. Don't rush this, go slow to temper the eggs without scrambling them.
Pour everything back into the saucepan and cook over medium heat, whisking constantly, until the mixture thickens and begins to bubble. It will take about 3-4 minutes for the mixture to start thickening ups. Once bubbling, cook for 1 more minute, still whisking. This step is important. The custard needs to fully bubble to activate the cornstarch and cook out any starchy taste.
Remove from heat and add the chopped chocolate, butter, and vanilla. Stir until completely melted and smooth.
8 oz. Dark to semi sweet chocolate, 2 teaspoon vanilla extract, 3 tablespoon unsalted butter
If you notice any lumps, pour the custard through a fine mesh strainer before adding to the crust.
Pour the custard into your chilled Oreo crust and smooth the top. Press plastic wrap directly onto the surface of the filling. Refrigerate for at least 4 hours, or overnight for best results.
Just before serving, beat the heavy whipping cream, powdered sugar, and vanilla on medium-high speed until stiff peaks form. Spread or pipe over the chilled pie and serve immediately.
1 ½ cups heavy whipping cream, 3 tablespoon powdered sugar, 1 teaspoon vanilla extract