For the crust, pulse the flour, salt, sugar, and butter together until the butter is pea-sized. Add the buttermilk and continue to pulse about 8 times. Once the flour sticks to itself when squeezed together, dump out dough onto a floured surface, and work it together into a disk. If the dough is too dry, add more buttermilk or water 1 tablespoon at a time. Cover with plastic wrap. Place in the fridge to chill for 30 minutes.

Roll out the dough on a floured work surface into a 12-inch round. Gently place into an 8-inch pie pan. Fold the overhang under itself and pinch the sides to create a pleat. Mix the egg yolk and cream together and brush onto the outside of the edges of the pie crust. Place back into the fridge to chill while the oven preheats to 400 degrees.

Once the pie crust has chilled, score the dough with the bottom of a fork, line with parchment paper and fill to the brim with pie weights or dried beans.

Bake in the preheated oven for 15 minutes, carefully remove the pie weights then place back into the oven to bake another 25-30 minutes, or until the crust has turned deep golden brown.

For the filling,

In a medium saucepan over medium heat, place in the heavy cream, pinot noir, brown sugar, and salt. Slice open one side of the vanilla bean and remove the seeds with the back of the knife. Add the vanilla beans to the cream along with the pod itself. Heat this mixture while stirring just until it starts to steam then remove from the heat. Add in the chocolate and let sit for 1 minute. Add in the butter and whisk the mixture vigorously until the chocolate has completely melted and a shiny, chocolate-y sauce appears. Pour into the prepared pie crust, cover with plastic wrap so that the plastic touches the chocolate and chill in the fridge for at least 4 hours.

Serve with whipped cream and chocolate shavings.