Begin by rolling out your all-butter pie crust onto a lightly floured surface. Carefully transfer the crust to a pie pan, pressing it against the edges. Use a fork to dock the base for steam release, then chill the unbaked crust in the refrigerator for 30 minutes.

Preheat your oven to 400°F (200°C). While the oven heats, toast the pecan halves on a baking sheet for 5-7 minutes until they're fragrant. Remove the crust from the fridge, line it with parchment paper, and fill with weights or beans. Blind bake for 15 minutes, then take out the weights and continue baking for an additional 5 minutes until lightly golden.

In a medium saucepan, melt the unsalted butter over medium-low heat. Stir continuously for 5-6 minutes until the butter turns a rich golden brown and emits a nutty aroma. Remove the pan from the heat and whisk in the chopped bittersweet chocolate until fully melted and smooth.

In a large mixing bowl, whisk together the sweetened condensed milk, brown sugar, and eggs until the mixture is smooth and well blended. Gradually add the melted chocolate mixture, Dutch process cocoa powder, vanilla bean paste, and a pinch of flaky sea salt. Finally, fold in the chopped pecans.

Pour the decadent filling into the pre-baked pie crust, spreading it evenly. Arrange additional pecan halves on top for an appealing presentation. Bake in the preheated oven at 350°F (175°C) for 35-45 minutes, or until the edges are puffed and the center remains slightly gooey.

Once baked, remove the pie from the oven and allow it to cool to room temperature for at least 1 hour. Then, transfer it to the refrigerator and let it chill for a minimum of 2 hours before serving.