Preheat oven to 350°F (175°C). Mix crushed cookies with melted butter and press into a 9-inch pie pan. Bake 10 minutes, then cool slightly.

For the brownie layer, melt 1/2 cup butter and semi-sweet chocolate in the microwave. Whisk in sugar, eggs, and vanilla. Fold in flour, cocoa powder, and salt.

Pour brownie batter over the crust. Bake at 350°F for 20-25 minutes until the edges are set. Let cool completely.

For the pudding, whisk sugar, cornstarch, salt, and milk in a saucepan over medium heat until thickened. Temper egg yolks with some hot milk, then return all to the pan and cook until very thick.

Remove pudding from heat. Stir in bittersweet chocolate, 2 tbsp butter, and vanilla until smooth.

Pour warm pudding over the cooled brownie layer. Cover with plastic wrap touching the surface and chill for at least 4 hours.

Before serving, whip heavy cream, powdered sugar, and vanilla to medium-stiff peaks. Spread over the pie and garnish with chocolate shavings.