Preheat oven to 425 degrees F. Mix sugar, flour and 3/4 cup of the buttermilk. Add beaten eggs, then the rest of the buttermilk, and mix well. Fold in melted butter. Add vanilla. Pour into pie shells. Bake at 425 degrees F. for 10 minutes, then turn oven down to 350 degrees F. and bake until firm, about 30 minutes. Sprinkle nutmeg on top of each. In any custard pie such as this, prevent a soggy crust by brushing the uncooked shell with a slightly-beaten egg white, then bake at 425 degrees F. for about 10 minutes. Fill and bake according to recipe.