Lemon-Sponge Pie
["2 eggs, separated", "1 c. sugar", "2 Tbsp. flour", "1 Tbsp. butter, softened", "1 lemon (juice and rind)", "1 c. milk", "1 tsp. vanilla"]
["Beat egg whites and set aside.", "Mix all other ingredients together.", "Fold in beaten egg whites last.", "Pour into an 8 or 9-inch pie shell.", "Bake at 420\u00b0 for 15 minutes; lower oven to 325\u00b0.", "Bake 20 minutes more.", "Test with a knife."]
["eggs", "sugar", "flour", "butter", "lemon", "milk", "vanilla"]