A Dixie Potato Pie

To half a pint of fresh milk, add one cupful of sweet potatoes, well mashed, with one tablespoonful of butter, and one-eighth cupful of cream, or milk. Beat until this is light and creamy. Into this mixture beat very lightly the yolks of four eggs; add nutmeg and sugar to taste and the grated rind of one lemon or one small orange. A white meringue may be added to the top if desired.