Sweet Potato Puffs
["2 lb. (3 c.) sweet potatoes, cooked and mashed", "3 Tbsp. margarine", "3/4 c. milk", "2 eggs, separated", "1/4 tsp. salt", "pinch of pepper"]
["Whip together sweet potatoes, butter, milk and pepper.", "Beat in egg yolks, whip egg whites with salt until stiff.", "Fold into sweet potatoes.", "Pile into buttered 1 1/2-quart casserole.", "Bake in 375\u00b0 oven for 30 minutes, or until puffed and top surface is lightly browned.", "Serves 6."]
["sweet potatoes", "margarine", "milk", "eggs", "salt", "pepper"]