Step 1

FOR THE CRUST: Adjust oven rack to middle position and heat oven to 350 degrees. In bowl of food processor fitted with steel blade, process cookies with 15 one-second pulses, then let machine run until crumbs are uniformly fine, about 15 seconds. (Alternatively, place cookies in large zipper-lock plastic bag and crush with rolling pin.) Transfer crumbs to medium bowl, drizzle with butter, and use fingers to combine until butter is evenly distributed.

Step 2

Pour crumbs into 9-inch Pyrex pie plate. Following illustration below, press crumbs evenly onto bottom and up sides of pie plate. Refrigerate lined pie plate 20 minutes to firm crumbs, then bake until crumbs are fragrant and set, about 10 minutes. Cool on wire rack while preparing filling.

Step 3

FOR THE FILLING: (See illustrations below). Bring half-and-half, salt, and about 3 tablespoons sugar to simmer in medium saucepan over medium-high heat, stirring occasionally with wooden spoon to dissolve sugar. Stir together remaining sugar and cornstarch in small bowl, then sprinkle over yolks and whisk, scraping down sides of bowl, if necessary, until mixture is glossy and sugar has begun to dissolve, about 1 minute. Whisk yolks thoroughly in medium bowl until slightly thickened, about 30 seconds. When half-and-half reaches full simmer, drizzle about 1/2 cup hot half-and-half over yolks, whisking constantly to temper; then whisk egg yolk mixture into simmering half-and-half (mixture should thicken in about 30 seconds). Return to simmer, whisking constantly, until 3 or 4 bubbles burst on the surface and mixture is thickened and glossy, about 15 seconds longer.

Step 4

Off heat, whisk in butter until incorporated; add chocolates and whisk until melted, scraping pan bottom with rubber spatula to fully incorporate. Stir in vanilla, then immediately pour filling into baked and cooled crust. Press plastic wrap directly on surface of filling and refrigerate pie until filling is cold and firm, about 3 hours.

Step 5

FOR THE TOPPING: Just before serving, beat cream, sugar, and vanilla in bowl of standing mixer on low speed until small bubbles form, about 30 seconds. Increase speed to medium; continue beating until beaters leave a trail, about 30 seconds more. Increase speed to high; continue beating until cream is smooth, thick, and nearly doubled in volume and forms soft peaks, about 20 seconds. Spread or pipe whipped cream over chilled pie filling. Cut pie into wedges and serve.