Sweet Potato Pie Recipe

4 eggs, separated
1-1/2 cups sugar
3 cups cooked, mashed sweet potatoes
1/2 cup softened margarine or butter
2 cups milk
2 teaspoons vanilla extract
1 teaspoon ground nutmeg
1- 1/2 teaspoons ground cinnamon
2 (9 inch) unbaked pie shells

Beat egg yolks until thick. Gradually add sugar; mix well. Add next 6 ingredients and mix well. Beat room temperature egg whites until stiff peaks form; fold into sweet potato mixture. Pour into pie shells and bake at 350° for 45 minutes or until set.