Preheat the oven to 350℉ (177℃).
While the crust bakes, combine the eggs, brown sugar, and salt in a medium bowl. Whisk well, then set aside.
2 large eggs, 2/3 cup (133g) packed dark brown sugar, 1/2 teaspoon salt
In a small saucepan over medium heat, melt the butter, then add the pecans. Cook, stirring frequently, for 5-7 minutes until slightly darkened and nutty smelling. Remove from the heat and set aside.
6 Tablespoons salted butter, 2 1/2 cups (300g) whole pecan halves
In another bowl, combine 1/2 cup of the buttered pecan halves with 1 Tablespoon of the whisked sugar and egg mixture. Toss well to coat, then spread onto a baking sheet lined with parchment paper. Bake in the preheated oven for 6-8 minutes until to toast and dry, then remove from the oven and let cool.
Finely chop the remaining 2 cups of buttered pecans. Add these to the brown sugar and egg mixture along with the remaining browned butter from toasting the pecans, the sour cream, and vanilla.
2 Tablespoons sour cream, 1 teaspoon pure vanilla extract
Pour the pecan filling into the pie crust and bake until mostly set but still slightly jiggly in the center, about 15 to 18 minutes. Let cool slightly while making the custard filling.
To make the custard, combine the cream and 1 cup of the milk in a medium pan over medium heat. Heat for 2-3 minutes just until steaming but do not let it come to a boil.
1 1/2 cups heavy cream, 1 cups whole milk
Meanwhile, whisk egg yolks, brown sugar, cornstarch, salt, and remaining 1/2 cup of milk in a medium bowl.
6 large egg yolks, 3/4 cup (150g) packed dark brown sugar, 1/3 cup (40g) cornstarch, 1/4 teaspoon salt, 0.5 cups whole milk
Temper the egg yolk mixture by whisking 1 cup of the hot milk mixture into the egg yolk mixture. This raises their temperature without scrambling them. Pour the tempered egg yolks back into the saucepan with the rest of the liquid and continue to cook over medium heat, stirring constantly, until thickened and bubbly, around 3-4 minutes.
Remove from the heat and whisk in the butter and vanilla extract until the butter has melted and everything is completely combined.
6 Tablespoons salted butter, 1 Tablespoon pure vanilla extract
Pour the warm custard over the pecan layer, then cover with plastic wrap pressed directly against the custard layer to prevent a skin from forming and chill for at least 4 hours to set.
To make the whipped cream topping, combine the heavy cream, sour cream powdered sugar, and vanilla in a medium bowl. Beat with an electric mixer until medium peaks form, then spread the whipped cream evenly over the pie. Sprinkle the candied pecan pieces on top before serving.
1 cup heavy cream, 1/4 cup sour cream, 3 Tablespoons powdered sugar, 1 teaspoon pure vanilla extract