Sweet Potato Pie
["1 1/2 c. sweet potatoes, cooked and mashed", "1 1/2 c. sugar", "2 1/2 Tbsp. margarine, softened", "2/3 c. evaporated milk", "3 egg yolks, beaten", "1 tsp. vanilla extract", "1 tsp. ground nutmeg", "3 egg whites, stiffly beaten", "1 (9-inch) deep dish pastry shell, unbaked"]
["Combine sweet potatoes, sugar and butter.", "Stir well.", "Stir in milk, egg yolks, vanilla and nutmeg.", "Set aside."]
["sweet potatoes", "sugar", "margarine", "milk", "egg yolks", "vanilla extract", "ground nutmeg", "egg whites", "pastry shell"]