Lemon Sponge Pie
["1 c. sugar", "1 Tbsp. butter", "4 Tbsp. flour (scant)", "2 egg yolks", "1 lemon (juice and rind)", "1 c. milk", "2 egg whites, beaten"]
["Cream the sugar and butter; add flour and beaten egg yolks. Mix in the lemon juice, lemon rind and milk gradually.", "Add beaten egg whites, but do not break whites all up.", "Bake at 350\u00b0 for 10 minutes, then 250\u00b0 for 1/2 to 3/4 hour."]
["sugar", "butter", "flour", "egg yolks", "lemon", "milk", "egg whites"]