Preheat the oven to 375°F (190°C) and lightly coat a 9-inch pie plate with nonstick cooking spray.
Combine the chopped pecans, softened butter, brown sugar, and salt in a bowl. Mix until the pecans are evenly coated and the mixture holds together when pressed.
Press the pecan mixture firmly into the bottom and up the sides of the pie plate to form an even crust.
Bake for 10–15 minutes, until fragrant and lightly browned. Remove from the oven and let the crust cool. Reduce the oven temperature to 300°F (150°C).
For the filling, combine the brown sugar, cornstarch, flour, butter, and salt in the top of a double boiler. Cook over medium-high heat, stirring until combined.
Add the beaten egg yolks and gradually whisk in the diluted sweetened condensed milk. Continue stirring constantly until the mixture thickens and smoothly coats the back of a spoon, about 5–7 minutes.
Stir in the vanilla extract and immediately pour the warm filling into the cooled pecan crust.
Bake at 300°F (150°C) for about 15 minutes, just until the filling is warmed through and lightly set.
Remove the pie from the oven and let it cool completely at room temperature.
Refrigerate for at least 2 hours, or until thoroughly chilled and firm.
Slice and serve each piece with a generous spoonful of whipped cream and a sprinkle of chopped pecans, if desired.