Irish Potato Custard Pie
["1 1/4 c. mashed potatoes", "1/2 tsp. salt", "1 c. sugar", "1/3 c. butter", "1 c. milk (half cream)", "4 egg yolks", "1 tsp. vanilla", "1 tsp. lemon", "4 egg whites, beaten stiff"]
["Whip potatoes and salt until light.", "Add sugar and butter while warm, then add milk and egg yolks.", "Last, fold in egg whites which have been beaten light.", "Put in unbaked shell.", "Bake in a 400\u00b0 oven until steel knife comes out clean."]
["potatoes", "salt", "sugar", "butter", "milk", "egg yolks", "vanilla", "lemon", "egg whites"]