Preheat your oven to 350°F (175°C). Fit your unbaked pie crust into a 9-inch pie dish and set aside.
In a medium saucepan, whisk together the sugar, flour, and salt. Slowly add the milk, whisking constantly to prevent lumps.
Cook over medium heat, stirring frequently, until the mixture thickens and begins to bubble (about 8–10 minutes).
Remove from heat and gradually whisk in the beaten eggs to temper them. Return the pan to low heat and cook for an additional 2–3 minutes, stirring constantly until thick and smooth.
Remove from heat again and stir in vanilla extract and chopped pecans.
Pour the creamy pecan filling into the prepared pie crust and smooth the top.
Bake for 30–35 minutes, or until the custard is set and lightly golden on top. The center should jiggle slightly but not be wet.
Let the pie cool completely at room temperature, then refrigerate for at least 1–2 hours before serving for best texture.
Top with whipped cream and additional chopped or halved pecans just before serving.
