Triple Chocolate Tart with Boozy Whipped Cream

Ingredients
Method
Preheat oven to 350°F with rack in middle.
Pulse almonds with cookies and sugar in a food processor until almonds and cookies are finely ground.
Add butter and pulse to combine, then press evenly onto bottom and up side of tart pan or 1-inch up side of springform pan (a dry measuring cup with a smooth bottom is very useful for pressing crumbs into an even layer).
Bake until set, 15 minutes. Cool on a rack 1 hour.
Whisk together milk, cream, stout, sugar, cornstarch, and cocoa in a medium saucepan and bring to a boil over medium heat, whisking constantly, then briskly simmer, whisking constantly, 2 minutes.
Remove from heat and whisk in chopped chocolate and vanilla until smooth.
Pour chocolate custard into cooled tart shell and cover surface with plastic wrap or wax paper (to prevent a skin from forming) and chill until set, about 3 hours.
Beat cream, bourbon, sugar, and vanilla in a bowl with an electric mixer just until stiff peaks form. Spread whipped cream decoratively on top of pie.
Garnish with chocolate shavings or dust with cocoa powder, if desired.