Preheat oven at 170° C. Prepare 20x20x7 pan. Line the base and grease the side.

Separate the eggs, place the white into a medium sized bowl. Beat eggs white until soft peak, gradually add sugar and beat until stiff. set aside.

Mix butter and 150gr sugar until pale and fluffy. Put Vanilla extract and beat for a while. Put in egg yolks one by one and beat well after each addition.

Put in half the flour and mix on low speed until incorporated. Put in milk in 2 addition and mixed until incorporated. Mix in balance of flour.

Put half the eggs white in and mix on low speed. Pour another half of eggs white in and fold.

Pour batter on pan and level.

Bake for 45 minutes or until skewer comes out clean. (i reduce to 150°C for the last 15 minutes because the top seems to be getting dark).