Place beaten eggs in a medium bowl. Gradually beat in sugar. Stir in melted butter, salt, flour, buttermilk, and vanilla extract. Mix until smooth. Pour mixture into pastry shell, and sprinkle top of the pie with nutmeg.
Bake in preheated oven for 50 minutes. Reduce heat to 325 degrees F (165 degrees C). Bake an additional 10 minutes. Pie is done when a toothpick inserted in center comes out clean.
Tips for making a buttermilk pie
I personally like to start all of my ingredients when they are room temperature. So that means I take my eggs out about 20 minutes before I need to use them. Baking is better when the temperatures of the ingredients start from as close of a range in temperatures as possible. I recommend purchasing commercial buttermilk for this recipe. I believe your results will be more consistent than making homemade buttermilk. This pie is best eaten while still warm. You should store this pie in the refrigerator. Custard pies should always be stored in the refrigerator. Warm this pie before serving