Preheat your oven to 350°F (175°C).
Place the pie crust in a 9-inch pie dish and set aside.
In a large bowl, whisk together the sugar, flour, and salt until well combined.
Add the buttermilk, melted butter, vanilla extract, and eggs to the bowl. Whisk until smooth and completely incorporated.
Pour the filling into the pie crust.
Bake the pie in the preheated oven for about 40-45 minutes, or until the top is golden brown and the centre is set.
Remove the pie from the oven and let it cool completely before serving.
Serve the buttermilk pie at room temperature or chilled. It can be served plain or topped with whipped cream or a sprinkle of powdered sugar if desired.