Preheat the oven to 325°F. Place your pie shell in the refrigerator to chill while you are making the pie.
In a large mixing bowl, using a hand mixer on medium-high speed, cream butter, and sugar until light and fluffy, about 2 to 3 minutes.
Add the flour and salt and beat for 15 to 30 seconds or until mixed in.
Add eggs, one at a time, beating after each egg until well mixed.
Add buttermilk and vanilla and continue beating until well combined.
Place your chilled pie shell onto a baking sheet, pour the buttermilk filling into the pie shell and place the baking sheet into the oven.
Bake for 60 minutes or until a knife inserted in the center comes out clean.
Remove from the oven. Cool on a wire rack until ready to serve.