Add the flour, sugar and salt into the bowl of a food processor and pulse to combine. Then add the cold butter and pulse until the butter is the size of lentils. Add the iced water and vinegar and pulse to help combine everything.
Placed a large piece of plastic wrap on your work bench and wrap the dough up. Squeeze the dough together into a disk and place in the fridge for 1 hour.
Preheat your oven to 170°C / 325°F. For this recipe you’ll need a 3” tall, 9-inch deep tart tin with removable bottom.
Once your dough has rested take it out of the fridge and unwrap it. Allow it to rest at room temperature for 10 minutes. Sprinkle a little flour on your work bench and your rolling pin and roll the dough out. Continue flipping the dough over and around as you roll it to ensure it’s all once even thickness. You want to roll it to about a 1/4-inch thickness and about 12” in diameter.
Sprinkle the rolling pin with a little flour and carefully drape the pastry dough over it to help you transfer it over your pie or tart tin. Carefully lift the edges and allow them to naturally fall into the edge and bottom of your tin. Cut off or fold the excess pie dough at the top leaving just a little bit of excess to go above the height of your pie tin. Use a fork to prick holes in the bottom of your pie crust. This will prevent it from bubbling up as it bakes.
Place some baking paper on the inside of your pie crust. Fill it with baking beads or dried beans like red beans or chickpeas. Bake on for 15 minutes.
Take the pie crust out of the oven and carefully lift the chickpeas out of the pie crust. Brush the bottom and sides of the pie crust with egg white. This will help seal up your pie crust to prevent liquids from leaking through the pie crust after having pricked it with the fork. Bake for a further 10 minutes. Once baked, allow to cool to room temp before adding filling.
Add the sugar, cocoa powder and cornstarch to a medium sized mixing bowl. Use a whisk to whisk together. Add the eggs and egg yolks and whisk until well combined. Add about 1/4 cup of the hot milk and whisk.
Place all of the mixture into a large saucepan along with the remaining milk. Whisk on medium heat until the mixture thickens. About 6 minutes. Add the chocolate and mix until melted into the custard.
Run the mixture through a sieve into the butter pie shell. Use a spoon or spatula to smoothen and spread out evenly. Chill in the fridge for 2 hours or overnight.
Add the heavy cream and vanilla extract to a large mixing bowl and whip to stiff peaks.
Add the whipped cream on top. Spread around using a spoon. Drizzle with chocolate sauce and swirl into the cream.Slice and serve.
This Pie can be stored in an airtight container for up to three days.