Preheat your oven to 350°F (175°C).

To make the crust, combine the flour and salt in a mixing bowl. Cut in the cold butter using a pastry cutter or fork until the mixture resembles coarse crumbs. Slowly add the ice water, one tablespoon at a time, mixing until the dough comes together.

Turn the dough out onto a floured surface and roll it into a 12-inch circle. Carefully transfer it to a 9-inch pie dish and trim any excess dough, folding the edges under to create a neat crust. Prick the bottom with a fork to prevent bubbling during baking.

Bake the crust for 10-12 minutes until lightly golden. Remove from the oven and set aside to cool.

For the filling, in a medium saucepan, combine the milk, heavy cream, sugar, cocoa powder, and cornstarch. Cook over medium heat, whisking constantly, until the mixture thickens and begins to boil.

Once the mixture starts to bubble, remove it from the heat and gradually whisk about a cup of the hot mixture into the beaten egg yolks. Return the egg mixture to the saucepan, continuing to whisk constantly. Bring the mixture to a boil again and cook for 2 more minutes until thickened.

Remove from the heat and stir in the butter, vanilla extract, and a pinch of salt until fully incorporated.

Pour the filling into the cooled pie crust and smooth the top with a spatula. Let the pie cool to room temperature, then refrigerate for at least 4 hours or until set.

Before serving, top with whipped cream and shaved chocolate, if desired.