Preheat oven at 375F or 190C
Mix flour, cornflour and baking powder together.
Melt butter, set aside to cool.
Beat egg whites, egg yolks, dry ingredients, suugar, ovalett, cold water together at medium speed until stiff.
Fold in melted butter (or oil)
Spread mixture onto a well greased swiss roll tin (check sizes above) tray lined with grease proof paper.
Bake for 15 minutes.
When cooled, spread evenly with jam or creanm then roll up the cake lightly.
Cut into desired width.