Step 1: Preheat oven to 350°F (175°C). Lightly spray a 9-inch pie pan with cooking spray.
Step 2: In a medium bowl, combine chopped pecans, softened butter, light brown sugar, and salt. Mix until the mixture is crumbly and holds together when pressed.
Step 3: Press the pecan mixture evenly into the bottom and up the sides of the prepared pie pan to form the crust.
Step 4: Bake the crust for about 10-12 minutes or until lightly toasted and fragrant. Remove from oven and set aside.
Step 5: In a medium saucepan, whisk together brown sugar, cornstarch, flour, and salt.
Step 6: Gradually stir in the blended sweetened condensed milk and water mixture.
Step 7: Cook over medium heat, stirring constantly, until the mixture thickens and comes to a gentle boil, about 5-7 minutes.
Step 8: Remove from heat and stir in butter until melted and smooth.
Step 9: Allow the mixture to cool slightly before whisking in the beaten egg yolks and vanilla extract.
Step 10: Pour the filling into the baked pecan crust and smooth the top.
Step 11: Chill the pie in the refrigerator for at least 4 hours or until set.
Step 12: Before serving, top with whipped cream as desired.