3 tbsp. butter
1/4 c. sugar
1/4 tsp. salt
1 egg yolk
3 tbsp. lemon juice
1 tsp. lemon peel
1/4 tsp. cinnamon
3 lg. sweet potatoes, cooked & mashed
1 c. milk
3 egg whites, beaten to stiff peaks
1 (9") unbaked pie shell

Heat oven to 350 degrees. Beat together butter, sugar and salt. Add egg yolk, lemon juice, lemon peel and cinnamon. Stir in sweet potatoes and milk; mix well. Fold in egg whites and pour into the pie shell. Bake for 40-50 minutes or until knife inserted in center comes out clean.