Place a rack in middle of oven; preheat to 350°F.

Stir together 1⅓ cups (161 g) chocolate wafer cookie crumbs, 5 Tbsp. unsalted butter, melted, and ¼ cup (50 g) granulated sugar in a medium bowl. Press on bottom and up sides of a 9” pie plate (1-qt. capacity). Bake crust until crisp, about 15 minutes. Transfer to a wire rack and let cool.

Whisk ⅔ cup (133 g) granulated sugar, ¼ cup (28 g) cornstarch, ½ tsp. Diamond Crystal or ¼ tsp. Morton kosher salt, and 4 large egg yolks in a 3-qt. heavy saucepan until combined well, then add 3 cups whole milk, room temperature, in a stream, whisking. Bring to a boil over medium heat, whisking, then reduce heat and simmer, whisking, about 1 minute (filling will be thick).

Strain filling through a fine-mesh sieve into a bowl, then whisk in 5 oz. fine-quality bittersweet chocolate (not unsweetened), melted, 2 oz. unsweetened chocolate, melted, 2 Tbsp. unsalted butter, softened, and 1 tsp. vanilla extract. Cover surface of filling with plastic wrap or a buttered round of parchment or wax paper and let cool completely, about 2 hours.

Spoon filling into crust and chill pie, loosely covered, at least 6 hours.

Just before serving, beat ¾ cup chilled heavy cream with 1 Tbsp. granulated sugar in a medium bowl using an electric mixer until it just holds stiff peaks, then spoon on top of pie. Do Ahead: Pie (without topping) can be chilled up to 1 day.

Editor's note: This easy dessert recipe was first printed in the February 2004 issue of ‘Gourmet.’ Head this way for a peanut butter pie with graham cracker crust (in case you want two dessert options) and more of our favorite pie recipes →