In deep bowl, beat egg yolks with 1/2 cup of the sugar for 3-5 minutes or until pale and thickened; blend in vanilla. In a separate bowl, beat egg whites until soft peaks form; gradually beat in remaining sugar until stiff glossy peaks form.
Combine flour with salt.
Alternately fold egg whites and flour mixture into yolk mixture, making 3 additions of whites and two of flour.
Spread evenly into waxed paper-lined 10x15x1/2" jelly roll pan.
Bake in 375 degree oven for 13-15 minutes or until top springs back when touched.
Dust clean tea towel with icing sugar.
Run knife around edge of cake; invert onto towel.
Carefully peel off paper.
Beginning at long side, immediately roll up cake tightly in towel.
Let cool.
Unroll cake and spread with marmalade.
Reroll tightly without towel.
Cake can be wrapped and stored up to 3 days ahead or frozen up to one week.