Lemon Sponge Pie
["1 c. sugar", "1 Tbsp. butter", "2 egg yolks", "3 Tbsp. flour", "grated rind of 1 lemon", "1 c. milk", "2 egg whites, beaten light"]
["Mix in order given and our into unbaked pie crust. Bake in moderate oven 25 minutes.", "You may use an orange instead of lemon; it's very good."]
["sugar", "butter", "egg yolks", "flour", "lemon", "milk", "egg whites"]