Garnish: chocolate shavings, chopped pecans, or cookie crumbs
Instructions:
Preheat the oven to 350°F.
Finely crush the cookies into fine crumbs by pulsing them in a food processor, Or, place the cookies in a heavy-duty ziplock bag and pound with a rolling pin until finely crushed. Stir together the cookie crumbs and melted butter in a small bowl until well combined.
Firmly press the crumb mixture into the bottom and up the sides of a 9-inch pie plate with deep sides.
Bake for 10 minutes. Let the crust cool while making the brownie layer.
Melt the butter and chocolate in a small microwave-safe bowl on high, stirring every 30 seconds, until melted, about 2 minutes.
In a separate medium bowl, whisk the eggs and sugar together until well combined, about 30 seconds. Whisk in the melted chocolate mixture, cocoa powder, vanilla, and salt. Stir in the flour with a spatula.
Pour the brownie batter into the crust and bake until puffed and set, about 20 minutes. Cool completely on a wire rack.
Once the brownie layer is cooled, place the egg yolks in a small heat-proof bowl and whisk just to loosen them up. Set aside.
In a medium saucepan, whisk together the sugar, cornstarch, and salt. Slowly whisk in the milk. Place over medium-high heat and cook, whisking frequently, until thickened, about 5 minutes.
Slowly whisk about ½ cup of the hot milk mixture into the yolks to temper them, then whisk the yolk mixture back into the saucepan. Cook over medium heat, stirring constantly, until thickened and bubbly, about 2 to 3 minutes. Remove from heat and stir in the chocolate, butter, and vanilla until fully melted and combined.
Pour the pudding over the brownie layer and let cool at room temperature for 20 minutes. Place the pie in the refrigerator, uncovered, to chill for at least 4 hours or overnight.
When ready to serve, beat the cream and sugar in a large mixing with an electric mixer at high speed until soft peaks form, about 2 minutes. Spread the whipped cream on top of the pie. Garnish with chocolate shavings, pecans, or cookie crumbs before slicing.