Beat egg yolks in a mixing bowl. Beat in molasses and sugar, then flour, butter, ginger, salt, milk, lemon peel and lemon juice to make a smooth mixture.
Beat egg whites until stiff but not dry. Fold into batter.
Pour mixture into greased 1½-qt. baking dish. Set in pan of hot water about 1" deep. Bake in slow oven (325°) 55 minutes or until top is brown