3 Egg yolks 1 c Sugar 1 T Flour 1 1/2 c Milk 1/2 t Lemon extract 1 t Lemon peel,grated 2 T Butter,at room temperature 1 c Sweet potatoes,mashed,cooked 1 Pie shell,unbaked,9" Sweetened whipped cream 1. Preheat oven to 400'F. 2. Beat egg yolks with sugar and flour. Add milk, lemon extract, lemon peel, butter, and mashed potatoes; beat until well blended. 3. Pour into unbaked pie shell and place on middle rack of preheated oven. Bake 10 minutes, then reduce heat to 325'F. and continue to bake until pie is firm. Serve warm topped with well-chilled sweetened whipping cream.