I just wanted to say that the chef is right the egg and sugar gets mixed until a leman colored then the flour little at a time folding the eggg whites so the cake dose not turn to rubber
I agree, it was hard to add the egg whites after making the egg yolk mixture more like a paste! I also added a splash of lemon juice and that gave it a tangy, yummy flavor!
I don't believe is OK to add the flour in egg yolks and sugar mixture because that become very hard composition and is dificult to incorporate the egg white because will lose the "fluffy". The best way is to add first the beated egg whites and after that little at a time the flour. I made a lot of cakes in my life and this is the best way for "Pan di Spagna" to make a good cake.