1. Preheat oven to 350°. In a food processor, pulse cookies until finely ground. Transfer to a medium bowl; set aside. To processor, add almonds and 3 tbsp. sugar and pulse until almonds have texture of coarse meal (be careful not to grind them into nut butter). Add ground nuts to cookies and stir in 6 tbsp. melted butter. Press into bottom and sides of a 9-in. deep-dish pie plate (crust should be fairly thick). Bake on center rack 15 minutes; let cool.
2. Put egg yolks in a medium bowl and beat to blend; set aside. In a medium saucepan over medium-high heat, stir together milk, 3/4 cup sugar, cornstarch, and salt. Bring to a gentle simmer, stirring constantly (mixture will begin to thicken). Reduce heat to medium.
3. Whisking constantly, pour 1/2 cup hot milk mixture into egg yolks, then pour egg-milk mixture into saucepan. Bring to a simmer (about 190° on an instant-read thermometer), stirring constantly with a wooden spoon (it will thicken noticeably). Remove from heat and stir in chocolate, vanilla, and 2 tbsp. butter.
4. Pour chocolate filling into a medium metal bowl, then set bowl in a larger bowl of ice and cold water and let cool 5 minutes, stirring constantly, until filling reaches room temperature. Pour filling into prepared crust and cover with plastic wrap, pressing it directly onto surface (to prevent a skin from forming). Chill until cold, at least 3 hours and up to 1 day.
5. Just before serving, combine cream and remaining 1 tbsp. sugar in a chilled bowl. With an electric mixer on high speed, beat cream until medium peaks form. Spread whipped cream in a thick dome over chocolate filling. Grate chocolate over pie.
Note: Nutritional analysis is per serving.
You can prepare this pie through step 4 up to 1 day ahead; top with whipped cream just before serving.