Make the crust: Preheat oven to 350 degrees. In a food processor, process cookies with 15 pulses and then let machine run for about 15 seconds straight until crumbs are uniformly fine. Put crumbs in a bowl and drizzle with butter. Use fingers to combine well.
Pour crumbs into 9-inch Pyrex pie plate. Press crumbs evenly over bottom and up the sides. Cover with a piece of plastic wrap and use a spoon or measuring cup to help press evenly. Keep covered and refrigerate for 20 minutes. Bake until crumbs are fragrant and set, about 10 minutes. Cool on wire rack and make pastry cream.
Bring half & half, salt and 3 tablespoons sugar to a simmer in a medium saucepan, stirring occasionally with a wooden spoon. Stir together remaining sugar and cornstarch and sprinkle over yolks. Whisk until mixture is glossy and sugar has begun to dissolve, about 1 minute. Whisk yolks thoroughly until slightly thickened. Temper the egg yolks by drizzling ½ cup of simmering half & half over the yolks, whisking constantly. Then whisk the yolk mixture into the simmering half & half, return to simmer, whisking constantly until thick and bubbly and glossy. It takes just a few minutes.
Remove from heat and whisk in the cold butter until incorporated. Add the two chocolates and whisk until melted, scraping the bottom and sides with a spatula to mix it all with no streaks. Stir in vanilla and then pour into baked crust. Press plastic wrap on the surface and refrigerate until cold and firm, about 3 hours.
Just before serving, make the whipped cream. Use chilled beaters and a chilled bowl. Beat cream, sugar and vanilla until soft peaks form. Takes a couple of minutes. Spread whipped cream over top of chilled pie and serve.