In a large bowl, combine sugar, flour and salt.
Add well beaten egg yolks, milk,
lemon juice and lemon peel; mix well.
In a separate bowl, beat egg whites
until stiff; fold into lemon mixture.
Pour into a greased 1-qt. baking dish.
Place baking dish in a pan of warm water.
Bake at 350° until a knife inserted
in center comes out clean, 35 min.
Serve warm with whipped cream,
if desired. Serves 6.