Directions

1. Preheat oven to 375 degrees. In a food processor, grind wafers and pecans until fine crumbs form. Add melted butter; process until moistened. Transfer mixture to a 9-inch pie plate; press into bottom and up sides (use the base of a dry measuring cup to help). Bake until fragrant, 8 to 10 minutes; let cool.
2. Place a large fine-mesh sieve over a medium bowl; set aside. In a medium saucepan, off heat, whisk together 2/3 cup sugar, cocoa powder, cornstarch, and salt. A few tablespoons at a time, whisk in milk, being sure to incorporate the cornstarch. Whisk in egg yolks.
3. Over medium heat, whisking constantly, cook mixture until the first large sputtering bubble forms. Reduce heat to low; continuing to whisk constantly, cook 1 minute. Remove from heat; immediately pour through sieve into bowl. Stir in teaspoon vanilla and 2 tablespoons cold butter.
4. Pour pudding into crust. Place plastic wrap directly on surface (to prevent skin from forming); chill at least 2 hours and up to 1 day. Just before serving, beat cream, remaining teaspoon sugar, and remaining teaspoon vanilla until soft peaks form. Spread whipped cream over pudding, and sprinkle with pecans.