100 gr. of butter
150 gr. emmentaler or parmesan cheese
1 spoon of flour
1 cup of milk
a bit of salt
Melt the butter and add the flour, then pour slowly the milk, while stirring with a wooden spoon, until it gains the consistency of a cream. Take away from stove and continue stirring until it chills down. When almost cold add 5 egg yolks one by one while stirring. In the end fold in the the beaten egg whites and then the grated cheese.
Butter a round oven tray and sift over some flour or fine dry bread crumbs, then pour in the prepared mix.
Place the tray in a larger pot filled with water (bain marie) and put in the oven. Turn the oven on to 180 C. and leave to bake for 1 hour.
Serve with sour cream.