2 cups mashed sweet potatoes
1/4 pound butter, softened
2 eggs, separated
1 cup packed brown sugar
1/4 teaspoon salt
1/2 teaspoon ground ginger
1/2 teaspoon ground cinnamon
1/2 teaspoon ground nutmeg
1/2 cup evaporated milk
1/4 cup white sugar
1 (9 inch) unbaked pie crust