Blend flour with sugar and salt, whisk in the melted butter (that is liquified but not sizzling. If it’s really hot, let it cool a bit before whisking in.) Beat the eggs and whisk them in. Add the buttermilk, vanilla and nutmeg. Pour into the baked pie shell. Slide the pie, still on the baking sheet, into the oven on a rack that has been placed in the lower third of the oven. Bake for 50-60 minutes at 350, or until a knife inserted in the pie comes clean. The center of the pie will still be a bit jiggly but will set up when cool. Cool on a wire rack.