Buttermilk Custard Pie
["1 unbaked 9-inch pastry crust", "3 Tbsp. butter or margarine", "3 egg yolks", "2/3 c. sugar", "2 Tbsp. flour", "1/2 tsp. salt", "1 2/3 c. buttermilk", "2 tsp. vanilla", "3 egg whites"]
["Prepare pastry crust.", "Melt butter or margarine; cool.", "Beat egg yolks slightly, stir in sugar, flour and salt.", "Add butter or margarine, buttermilk and vanilla.", "Beat egg whites until soft peaks form; fold into buttermilk mixture.", "Pour into crust.", "Bake at 450\u00b0 for 10 minutes.", "Reduce heat to 350\u00b0, bake 15 to 20 minutes or until knife inserted in pie center comes out clean and pie is golden brown.", "Cool and chill before serving."]
["pastry crust", "butter", "egg yolks", "sugar", "flour", "salt", "buttermilk", "vanilla", "egg whites"]