So, make a béchamel sauce with 60 gr. of flour, 60 gr. of butter, and 400 ml of milk. When it's done fold in 4 egg yolks, one at
a time (I wait for the béchamel to be a bit cooler) and then 150 gr. of
grated cheese (parmigiano, or gruyere, or condé or emmenthal, or a
mixture of these). Finally incorporate 5 egg whites beaten till they are
white solid snow. I make individual ones but you can make a big one
(good in lunch boxes and you can freeze them). Put in the mold(s) with
butter around so they won't stick and cook at 375 degrees for around a
half hour, without opening the oven.