First, make the roux. In a tall pot, let the butter foam well, add the flour all at once and let it cook for 2 to 3 minutes.
Add a little more than half of the milk and whisk out the lumps until you have a thick smooth paste.
Add the rest of the milk and let everything simmer again for 2 to 3 minutes while stirring firmly.
Now mix in all the cheeses vigorously, stir again until it puffs on the fire.
Mix the eggs with the cream and season with pepper, salt, and nutmeg.
Add this last and stir vigorously until it puffs on the fire again.
Grease a square or rectangular dish well with oil, pour in the cheese mixture.
Cover this with plastic wrap, you can also cover the dish with plastic wrap that you press well into the edges.
Let it set in the fridge for 1 night.
Remove the top plastic, turn it out onto a board and remove from the mold.
Remove the plastic.
Cut the mixture into equal squares, coat in flour and give it the desired shape, can be round or oval, whichever you find easiest.
Make sure there are no bare spots without flour, dip in the egg white, cover all around again, and finally coat well all around with breadcrumbs, sprinkle some breadcrumbs on a plate and place the breaded croquettes on top.
You can keep them wrapped in the fridge for 5 days, or you can also freeze them.
Fry them for 4 minutes at 175°, place them not too close together in your fryer.
If they are frozen, fry them for 2 minutes longer, depending on the thickness of your croquettes.
