Graham Cracker Crust:
140g biscuits (I used Arnotts Marie biscuits)
2 Tbl. sugar
71g salted butter, melted and warm
Chocolate Cream Filling:
113g salted butter, cut into 1/2" cubes and chilled
1 3/4 cups milk
1 3/4 cups cream
9 egg yolks
310g bittersweet chocolate, finely chopped
2 tsp. instant espresso or coffee (optional)
1 1/2 tsp. vanilla extract
Whipped Cream to Top:
2 cups heavy cream
2 Tbl. sugar
1 tsp. vanilla extract
Optional: bittersweet chocolate, to garnish
To Bake Graham Cracker Crust:
Place oven rack in middle position, and preheat oven to 160°.
Roughly break biscuits, then pulverize to a fine powder in a food processor, about 30 seconds. Add sugar, and pulse briefly to combine. Add melted butter through feed tube in a slow, steady stream, pulsing as you go to combine, until mixture resembles the sand where ocean meets beach.
(Alternatively, to make crust by hand, place crackers in a heavy-duty Ziploc and steamroller them with a rolling pin, until they are powder. Pour crumbs into a medium bowl, stir in sugar to combine, and drizzle melted butter over all, stirring and mooshing until mixture resembles wet sand.)
Transfer the crumbs to a 9" pie plate. Spread lightly to distribute, then gently, firmly, press crumbs into bottom and up sides of pie plate, using the bottom of a measuring cup or small ramekin. It will remain very loose; aim for general coverage. The crust will firm up considerably as it bakes. Bake 15-18 minutes, until your kitchen is filled with good smells, and the crust is lightly browned. Cool completely while making the filling.
To Assemble Filling:
Heat the milk and cream in a large saucepan over medium-high heat, until it's steaming and just barely reached a simmer. Remove pan from heat. In a large bowl, whisk together 2/3 cup sugar and the corn flour. Add egg yolks, and whisk until smooth. Slowly, steadily, drizzle hot cream-milk into the egg yolk-sugar mixture, whisking constantly, until smooth. You are tempering the egg yolks here, to prevent them from scrambling. Return tempered yolk/milk-cream mixture to the large saucepan, and heat over medium heat, stirring often, until bubbles rise to the surface and mixture is very thick, like pudding, 3-4 minutes. Remove pan from heat, and to the hot pudding mixture, slowly, in batches, add the 113g cold butter and 310g chopped chocolate, whisking until smooth. Whisk in instant espresso, if using, until smooth. Stir in the 1 1/2 teaspoons of vanilla.
Set a fine-meshed sieve over a deep bowl, and strain chocolate mixture. Pour pudding into strainer in batches, and press with a spatula to encourage. This is fussy but fast, a few minutes at most, and is key to achieving that sublime creamy texture. You'll see when your done all the inevitable cornstarch lumps and eggy bits left behind in the strainer, which is such a much better place for them than the pie.
Cover filling with plastic wrap, pressing down right to the surface to prevent a skin from forming, and refrigerate until set, about 4 hours.
To Assemble Pie:
When filling is firm, remove plastic wrap and stir until smooth. Spoon chilled filling into reserved, cooled crust, forming a dome in the center with a rubber spatula for a more polished look, or piling it high in the middle for a more casual affair.
In a large bowl, whip the cream, sugar and vanilla until soft but strong-ish peaks form. Dollop cream on top of filling, as much as you dare, and with a peeler, shave a little additional chocolate over all, if you fancy.